67 lines
1.7 KiB
Plaintext
67 lines
1.7 KiB
Plaintext
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created: 20150103184022184
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modified: 20150103184022184
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title: $:/plugins/tiddlywiki/railroad/syntax
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The railroad widget constructs a diagram from the components defined below.
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`x` and `y` here stand for any component.
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---
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; sequence
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: <$railroad text=""" ["<-"] {x} ["->"] """/>
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* A sequence of components
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* The `<-` and `->` delimiters allow you to force a single component to be treated as a sequence. This is occasionally useful for spacing a diagram out
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---
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; optional
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: <$railroad text=""" "[" [":"] x "]" """/>
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* A component that can be omitted
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* The colon makes `x` appear straight ahead
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---
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; repeated
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: <$railroad text=""" "{" x [:"+" y] "}" """/>
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* A list of one or more `x`
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* The `+` suffix adds `y` as a separator between each `x` and the next
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---
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; optional repeated
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: <$railroad text=""" "[{" [":"] x [:"+" y] "}]" """/>
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* An optional list of `x`, i.e. a list of zero or more `x`
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---
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; choice
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: <$railroad text=""" "(" {[:":"] x +"|"} ")" """/>
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* A set of alternatives
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* The colon indicates which branch appears straight ahead. By default, it's the first branch
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---
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; string / terminal
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: <$railroad text={{$:/plugins/tiddlywiki/railroad/syntax-string}}/>
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* A literal or terminal component
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* This follows the normal ~TiddlyWiki rules for quoted strings
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---
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; nonterminal
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: <$railroad text=""" (name | "<" string ">") """/>
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* A nonterminal component, i.e. the name of another diagram
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* The simple `name` option is available when the text starts with a letter and contains only letters, digits, underscores, dots and hyphens
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---
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; comment
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: <$railroad text=""" "/" string "/" """/>
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* A comment
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---
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; dummy
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: <$railroad text=""" "-" """/>
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* The absence of a component
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