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<!-- Weave of 'Linked Lists and Stacks' generated by Inweb -->
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< ul class = "crumbs" > < li > < a href = "../index.html" > Home< / a > < / li > < li > < a href = "index.html" > foundation< / a > < / li > < li > < a href = "index.html#2" > Chapter 2: Memory, Streams and Collections< / a > < / li > < li > < b > Linked Lists and Stacks< / b > < / li > < / ul > < / div >
< p class = "purpose" > A simple implementation for single-linked lists of objects allocated by Foundation's memory manager, and for last-in-first-out stacks of same.< / p >
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< ul class = "toc" > < li > < a href = "2-llas.html#SP1" > § 1. Implementation< / a > < / li > < li > < a href = "2-llas.html#SP6" > § 6. A function call API< / a > < / li > < li > < a href = "2-llas.html#SP7" > § 7. A macro-ized API< / a > < / li > < li > < a href = "2-llas.html#SP9" > § 9. LIFO stacks< / a > < / li > < / ul > < hr class = "tocbar" >
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< p class = "commentary firstcommentary" > < a id = "SP1" class = "paragraph-anchor" > < / a > < b > § 1. Implementation. < / b > Basically, there's a head structure, which points to a chain of body structures,
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each linking to the next. But to reduce memory manager overhead, we're going to store
the first few body structures inside the head structure: that way, for a list of just
a few items, only one call to the memory manager is needed.
< / p >
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< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "constant-syntax" > NO_LL_EARLY_ITEMS< / span > < span class = "plain-syntax" > < / span > < span class = "constant-syntax" > 32< / span >
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< / pre >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > typedef< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > first_list_item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > last_list_item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > linked_list_length< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > early_items< / span > < span class = "plain-syntax" > [< / span > < span class = "constant-syntax" > NO_LL_EARLY_ITEMS< / span > < span class = "plain-syntax" > ];< / span >
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< span class = "plain-syntax" > < / span > < span class = "constant-syntax" > CLASS_DEFINITION< / span >
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< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > ;< / span >
< span class = "reserved-syntax" > typedef< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > item_contents< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > struct< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > next_list_item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > ;< / span >
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< / pre >
< ul class = "endnotetexts" > < li > The structure linked_list is private to this section.< / li > < li > The structure linked_list_item is private to this section.< / li > < / ul >
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< p class = "commentary firstcommentary" > < a id = "SP2" class = "paragraph-anchor" > < / a > < b > § 2. < / b > < / p >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LinkedLists::new< / span > < button class = "popup" onclick = "togglePopup('usagePopup1')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup1" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::new< / span > < / span > :< br / > < a href = "2-llas.html#SP7" > § 7< / a > , < a href = "2-llas.html#SP10" > § 10< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > ll< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > CREATE< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ll< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > linked_list_length< / span > < span class = "plain-syntax" > = < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ll< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ll< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > ll< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP3" class = "paragraph-anchor" > < / a > < b > § 3. < / b > The following runs in constant time, i.e., performs no loops. In general we
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want speed rather than memory efficiency.
< / p >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > LinkedLists::add< / span > < button class = "popup" onclick = "togglePopup('usagePopup2')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup2" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::add< / span > < / span > :< br / > < a href = "2-llas.html#SP7" > § 7< / a > , < a href = "2-llas.html#SP10" > § 10< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > to_end< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "null list"< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > linked_list_length< / span > < span class = "plain-syntax" > < < / span > < span class = "constant-syntax" > NO_LL_EARLY_ITEMS< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > = & (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > early_items< / span > < span class = "plain-syntax" > [< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > linked_list_length< / span > < span class = "plain-syntax" > ]);< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > else< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > CREATE< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > CREATE< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > item_contents< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > to_end< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > else< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > } < / span > < span class = "reserved-syntax" > else< / span > < span class = "plain-syntax" > {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_list_item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > first_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > linked_list_length< / span > < span class = "plain-syntax" > ++;< / span >
< span class = "plain-syntax" > }< / span >
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< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP4" class = "paragraph-anchor" > < / a > < b > § 4. < / b > Because of the direction of the links, only removing from the front is quick:
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< / p >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LinkedLists::remove_from_front< / span > < button class = "popup" onclick = "togglePopup('usagePopup3')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup3" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::remove_from_front< / span > < / span > :< br / > < a href = "2-llas.html#SP5" > § 5< / a > , < a href = "2-llas.html#SP10" > § 10< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "null list"< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > first_list_item< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "empty list can't be popped"< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > top< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_list_item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > top< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "identifier-syntax" > first_list_item< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > linked_list_length< / span > < span class = "plain-syntax" > --;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > top< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > item_contents< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
2020-04-24 10:26:18 +00:00
< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP5" class = "paragraph-anchor" > < / a > < b > § 5. < / b > It's rather slower to delete from a known position in the middle:
2019-02-04 22:26:45 +00:00
< / p >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LinkedLists::delete< / span > < button class = "popup" onclick = "togglePopup('usagePopup4')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup4" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::delete< / span > < / span > :< br / > < a href = "2-llas.html#SP7" > § 7< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ) {< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "null list"< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > < < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ) || (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > > = < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > linked_list_length< / span > < span class = "plain-syntax" > )) < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "index not valid"< / span > < span class = "plain-syntax" > );< / span >
2020-04-21 23:52:25 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > == < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ) < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < a href = "2-llas.html#SP4" class = "function-link" > < span class = "function-syntax" > LinkedLists::remove_from_front< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > );< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_list_item< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > --;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > == < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ) {< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > ) < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > contents_deleted< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > item_contents< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > linked_list_length< / span > < span class = "plain-syntax" > --;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > contents_deleted< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > }< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > internal_error< / span > < span class = "plain-syntax" > (< / span > < span class = "string-syntax" > "index not found"< / span > < span class = "plain-syntax" > );< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP6" class = "paragraph-anchor" > < / a > < b > § 6. A function call API. < / b > < / p >
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< pre class = "displayed-code all-displayed-code code-font" >
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< span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "function-syntax" > LinkedLists::len< / span > < button class = "popup" onclick = "togglePopup('usagePopup5')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup5" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::len< / span > < / span > :< br / > < a href = "2-llas.html#SP10" > § 10< / a > < br / > Time - < a href = "3-tm.html#SP7" > § 7< / a > < br / > Epub Ebooks - < a href = "5-ee.html#SP7_3" > § 7.3< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > linked_list_length< / span > < span class = "plain-syntax" > ):0;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LinkedLists::first< / span > < button class = "popup" onclick = "togglePopup('usagePopup6')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup6" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::first< / span > < / span > :< br / > < a href = "2-llas.html#SP7" > § 7< / a > < br / > Version Numbers - < a href = "7-vn.html#SP8" > § 8< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_list_item< / span > < span class = "plain-syntax" > ):< / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LinkedLists::entry< / span > < button class = "popup" onclick = "togglePopup('usagePopup7')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup7" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::entry< / span > < / span > :< br / > < a href = "2-llas.html#SP7" > § 7< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > int< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > , < / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > < < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > ) || (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > == < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ) || (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > > = < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > linked_list_length< / span > < span class = "plain-syntax" > )) < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > first_list_item< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > ; < / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > if< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > -- == < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > item_contents< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LinkedLists::last< / span > < button class = "popup" onclick = "togglePopup('usagePopup8')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup8" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::last< / span > < / span > :< br / > < a href = "2-llas.html#SP7" > § 7< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ) {< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > last_list_item< / span > < span class = "plain-syntax" > ):< / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LinkedLists::next< / span > < button class = "popup" onclick = "togglePopup('usagePopup9')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup9" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::next< / span > < / span > :< br / > < a href = "2-llas.html#SP7" > § 7< / a > < br / > Version Numbers - < a href = "7-vn.html#SP8" > § 8< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > ) {< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > next_list_item< / span > < span class = "plain-syntax" > ):< / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
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< span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *< / span > < span class = "function-syntax" > LinkedLists::content< / span > < button class = "popup" onclick = "togglePopup('usagePopup10')" > < span class = "comment-syntax" > ?< / span > < span class = "popuptext" id = "usagePopup10" > Usage of < span class = "code-font" > < span class = "function-syntax" > LinkedLists::content< / span > < / span > :< br / > < a href = "2-llas.html#SP7" > § 7< / a > < br / > Version Numbers - < a href = "7-vn.html#SP8" > § 8< / a > < / span > < / button > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > ) {< / span >
2020-04-21 16:55:17 +00:00
< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > return< / span > < span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > ?(< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > -> < / span > < span class = "element-syntax" > item_contents< / span > < span class = "plain-syntax" > ):< / span > < span class = "identifier-syntax" > NULL< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > }< / span >
2020-04-24 10:26:18 +00:00
< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP7" class = "paragraph-anchor" > < / a > < b > § 7. A macro-ized API. < / b > These intentionally hide the implementation. The difference between
2020-04-22 22:57:09 +00:00
< span class = "extract" > < span class = "extract-syntax" > FIRST_IN_LINKED_LIST< / span > < / span > and < span class = "extract" > < span class = "extract-syntax" > FIRST_ITEM_IN_LINKED_LIST< / span > < / span > is that one returns
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the first structure in the list, and the other returns the first
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< span class = "extract" > < span class = "extract-syntax" > linked_list_item< / span > < / span > chunk in the list. From the latter you can make the
former using < span class = "extract" > < span class = "extract-syntax" > CONTENT_IN_ITEM< / span > < / span > , but not vice versa. The same object
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may be listed in many different lists, so if all you have is the object,
you don't know its place in the list.
< / p >
2020-04-25 10:33:39 +00:00
< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > NEW_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > )< / span >
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< span class = "plain-syntax" > (< / span > < a href = "2-llas.html#SP2" class = "function-link" > < span class = "function-syntax" > LinkedLists::new< / span > < / a > < span class = "plain-syntax" > ())< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > FIRST_ITEM_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::first< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > ENTRY_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > *) (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::entry< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > DELETE_FROM_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > *) (< / span > < a href = "2-llas.html#SP5" class = "function-link" > < span class = "function-syntax" > LinkedLists::delete< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > N< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > LAST_ITEM_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::last< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > NEXT_ITEM_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::next< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > ))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > CONTENT_IN_ITEM< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > *) (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::content< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > )))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > ADD_TO_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < a href = "2-llas.html#SP3" class = "function-link" > < span class = "function-syntax" > LinkedLists::add< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > , (< / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *) (< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > ), < / span > < span class = "constant-syntax" > TRUE< / span > < span class = "plain-syntax" > )< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > FIRST_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > *) (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::content< / span > < / a > < span class = "plain-syntax" > (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::first< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ))))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > LAST_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > *) (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::content< / span > < / a > < span class = "plain-syntax" > (< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::last< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ))))< / span >
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< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP8" class = "paragraph-anchor" > < / a > < b > § 8. < / b > The following macro requires slight care to use: the list < span class = "extract" > < span class = "extract-syntax" > L< / span > < / span > needs to be
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calculable without side-effects. There's no such worry over < span class = "extract" > < span class = "extract-syntax" > P< / span > < / span > or < span class = "extract" > < span class = "extract-syntax" > T< / span > < / span > , since
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they're just identifier names: the loop variable and the type name respectively.
< / p >
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< p class = "commentary" > Note that the loop variable < span class = "extract" > < span class = "extract-syntax" > P< / span > < / span > must already be defined. Inside the loop body,
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a new variable will also then exist, < span class = "extract" > < span class = "extract-syntax" > P_item< / span > < / span > , to refer to the item which
points to < span class = "extract" > < span class = "extract-syntax" > P< / span > < / span > . This allows us to iterate despite the comments above.
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< / p >
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< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > LOOP_OVER_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
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< span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > for< / span > < span class = "plain-syntax" > (< / span > < span class = "reserved-syntax" > linked_list_item< / span > < span class = "plain-syntax" > *< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _item< / span > < span class = "plain-syntax" > = (< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > FIRST_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ), < / span > < span class = "identifier-syntax" > FIRST_ITEM_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ));< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _item< / span > < span class = "plain-syntax" > ;< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _item< / span > < span class = "plain-syntax" > = (< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > = < / span > < span class = "identifier-syntax" > CONTENT_IN_ITEM< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > NEXT_ITEM_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _item< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > ), < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > ), < / span > < span class = "identifier-syntax" > NEXT_ITEM_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > ##< / span > < span class = "identifier-syntax" > _item< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > )))< / span >
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< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP9" class = "paragraph-anchor" > < / a > < b > § 9. LIFO stacks. < / b > The above gives us an almost free implementation of LIFO, last-in-first-out,
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stacks, where we represent a stack as a linked list whose first entry is at
the front. To push an item, we add it at the front; to pull, we remove the
front iten.
< / p >
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< p class = "commentary" > We provide an abstract type name for these stacks, even though they're the
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exact same structure. For reasons to do with the way < span class = "extract" > < span class = "extract-syntax" > typedef< / span > < / span > works in C,
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it is awkward to typedef the two names together, so we'll simply use the
preprocessor:
< / p >
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< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "constant-syntax" > lifo_stack< / span > < span class = "plain-syntax" > < / span > < span class = "reserved-syntax" > linked_list< / span >
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< / pre >
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< p class = "commentary firstcommentary" > < a id = "SP10" class = "paragraph-anchor" > < / a > < b > § 10. < / b > Otherwise, it's macros all the way:
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< / p >
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< pre class = "definitions code-font" > < span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > NEW_LIFO_STACK< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > )< / span >
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< span class = "plain-syntax" > (< / span > < a href = "2-llas.html#SP2" class = "function-link" > < span class = "function-syntax" > LinkedLists::new< / span > < / a > < span class = "plain-syntax" > ())< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > PUSH_TO_LIFO_STACK< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < a href = "2-llas.html#SP3" class = "function-link" > < span class = "function-syntax" > LinkedLists::add< / span > < / a > < span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ), (< / span > < span class = "reserved-syntax" > void< / span > < span class = "plain-syntax" > *) (< / span > < span class = "identifier-syntax" > I< / span > < span class = "plain-syntax" > ), < / span > < span class = "constant-syntax" > FALSE< / span > < span class = "plain-syntax" > )< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > PULL_FROM_LIFO_STACK< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > ((< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > *) < / span > < a href = "2-llas.html#SP4" class = "function-link" > < span class = "function-syntax" > LinkedLists::remove_from_front< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > POP_LIFO_STACK< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > (< / span > < a href = "2-llas.html#SP4" class = "function-link" > < span class = "function-syntax" > LinkedLists::remove_from_front< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ))< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > TOP_OF_LIFO_STACK< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > FIRST_IN_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > LIFO_STACK_EMPTY< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > ((< / span > < a href = "2-llas.html#SP6" class = "function-link" > < span class = "function-syntax" > LinkedLists::len< / span > < / a > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > ) == < / span > < span class = "constant-syntax" > 0< / span > < span class = "plain-syntax" > )?< / span > < span class = "identifier-syntax" > TRUE:FALSE< / span > < span class = "plain-syntax" > )< / span >
< span class = "definition-keyword" > define< / span > < span class = "identifier-syntax" > LOOP_DOWN_LIFO_STACK< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
< span class = "plain-syntax" > < / span > < span class = "identifier-syntax" > LOOP_OVER_LINKED_LIST< / span > < span class = "plain-syntax" > (< / span > < span class = "identifier-syntax" > P< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > T< / span > < span class = "plain-syntax" > , < / span > < span class = "identifier-syntax" > L< / span > < span class = "plain-syntax" > )< / span >
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< / pre >
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< nav role = "progress" > < div class = "progresscontainer" >
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< ul class = "progressbar" > < li class = "progressprev" > < a href = "2-mth.html" > ❮ < / a > < / li > < li class = "progresschapter" > < a href = "P-abgtf.html" > P< / a > < / li > < li class = "progresschapter" > < a href = "1-fm.html" > 1< / a > < / li > < li class = "progresscurrentchapter" > 2< / li > < li class = "progresssection" > < a href = "2-dl.html" > dl< / a > < / li > < li class = "progresssection" > < a href = "2-mmr.html" > mmr< / a > < / li > < li class = "progresssection" > < a href = "2-fc.html" > fc< / a > < / li > < li class = "progresssection" > < a href = "2-lcl.html" > lcl< / a > < / li > < li class = "progresssection" > < a href = "2-str.html" > str< / a > < / li > < li class = "progresssection" > < a href = "2-wal.html" > wal< / a > < / li > < li class = "progresssection" > < a href = "2-mth.html" > mth< / a > < / li > < li class = "progresscurrent" > llas< / li > < li class = "progresssection" > < a href = "2-dct.html" > dct< / a > < / li > < li class = "progresssection" > < a href = "2-trs.html" > trs< / a > < / li > < li class = "progresschapter" > < a href = "3-em.html" > 3< / a > < / li > < li class = "progresschapter" > < a href = "4-chr.html" > 4< / a > < / li > < li class = "progresschapter" > < a href = "5-htm.html" > 5< / a > < / li > < li class = "progresschapter" > < a href = "6-bf.html" > 6< / a > < / li > < li class = "progresschapter" > < a href = "7-vn.html" > 7< / a > < / li > < li class = "progresschapter" > < a href = "8-ws.html" > 8< / a > < / li > < li class = "progressnext" > < a href = "2-dct.html" > ❯ < / a > < / li > < / ul > < / div >
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< / nav > <!-- End of weave -->
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< / main >
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< / body >
< / html >
