94 lines
2.8 KiB
Plaintext
94 lines
2.8 KiB
Plaintext
created: 20240310165023000
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modified: 20240310175033730
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tags: [[Procedure Syntax]]
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title: Procedure Definition Syntax
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type: text/vnd.tiddlywiki
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<<.preamble """What follows is a formal presentation of the syntax of the [[Pragma: \procedure]], using [[railroad diagrams|Railroad Diagrams]]. """>>
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! \procedure
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There are 2 types of procedure definitions
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* Single line definitions
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* Multi line definitions
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!! Single Line
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Single line definitions should only be used for very short bodies, where the procedure name, params and the body fit into 1 line terminated with a line-feed.
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<$railroad text="""
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"\procedure"
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[[<"space">|"Filter Whitespace"]]
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"procedure-name"
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<"(params)">
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[:[[<"space">|"Filter Whitespace"]]]
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"body"
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"lf"
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"""/>
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!! Multi Line
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The majority of procedure definitions will have a body, that spans over several lines of wikitext. Those procedure definitions are terminated using the "\end" pragma
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<$railroad text="""
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"\procedure"
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[[<"space">|"Filter Whitespace"]]
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"procedure-name"
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<"(params)">
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[:[[<"space">|"Filter Whitespace"]]]
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body
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"\end"
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"""/>
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The [[procedure-name|Procedures]] is a sequence of non-whitespace characters other than `(` or `>`.
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* <<.place procedure-name>> is a sequence of letters (`A`--`Z`, `a`--`z`), digits (`0`--`9`), hyphens (`-`) and underscores (`_`)
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* <<.place body>> is wikitext including [[nested procedures|Pragma: \procedure]]
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* <<.place space>> denotes a sequence of [[whitespace characters|Filter Whitespace]]
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!! params
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The parameter declaration list <<.place (params)>> has the following syntax:
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<$railroad text="""
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\start none
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\end none
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"(" [:"sep"] [:{ parameter "sep" }] ")"
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"""/>
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* <<.place sep>> is any sequence of characters that does not match a <<.place param-name>>. <br>Among other things, this includes commas, spaces and linefeeds.
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Each ''individual'' <<.place parameter>> has the following syntax:
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<$railroad text="""
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\start none
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\end none
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"param-name" [: [:[[<"space">|"Filter Whitespace"]]] ":" [:[[<"space">|"Filter Whitespace"]]] default ]
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"""/>
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* <<.place param-name>> is a sequence of letters (`A`--`Z`, `a`--`z`), digits (`0`--`9`), hyphens (`-`) and underscores (`_`).
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* <<.place default>> is an optional value of a parameter is specified as follows:
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<$railroad text={{$:/editions/tw5.com/railroad/macro-parameter-value}}/>
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!! body
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The <<.place body>> of the definition has the following syntax:
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<$railroad text="""
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\start none
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\end none
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{[[<"wikitext">|WikiText]] "lf"}
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"""/>
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* <<.place wikitext>> is any sequence of characters that doesn't terminate the macro definition.
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** If [[nested procedures|Pragma: \procedure]] are used they need to be at the start of the wikitext. There are the same rules as if the wikitext would be in a tiddler.
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** Pragmas need to be before standard wikitext.
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* <<.place lf>> denotes a linefeed.
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