<!DOCTYPE html> <html> <head> <title>grammar.coffee</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <meta name="viewport" content="width=device-width, target-densitydpi=160dpi, initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"> <link rel="stylesheet" media="all" href="docco.css" /> </head> <body> <div id="container"> <div id="background"></div> <ul id="jump_to"> <li> <a class="large" href="javascript:void(0);">Jump To …</a> <a class="small" href="javascript:void(0);">+</a> <div id="jump_wrapper"> <div id="jump_page"> <a class="source" href="browser.html"> browser.coffee </a> <a class="source" href="cake.html"> cake.coffee </a> <a class="source" href="coffee-script.html"> coffee-script.coffee </a> <a class="source" href="command.html"> command.coffee </a> <a class="source" href="grammar.html"> grammar.coffee </a> <a class="source" href="helpers.html"> helpers.coffee </a> <a class="source" href="index.html"> index.coffee </a> <a class="source" href="lexer.html"> lexer.coffee </a> <a class="source" href="nodes.html"> nodes.coffee </a> <a class="source" href="optparse.html"> optparse.coffee </a> <a class="source" href="repl.html"> repl.coffee </a> <a class="source" href="rewriter.html"> rewriter.coffee </a> <a class="source" href="scope.html"> scope.litcoffee </a> <a class="source" href="sourcemap.html"> sourcemap.litcoffee </a> </div> </li> </ul> <ul class="sections"> <li id="title"> <div class="annotation"> <h1>grammar.coffee</h1> </div> </li> <li id="section-1"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-1">¶</a> </div> <p>The CoffeeScript parser is generated by <a href="http://github.com/zaach/jison">Jison</a> from this grammar file. Jison is a bottom-up parser generator, similar in style to <a href="http://www.gnu.org/software/bison">Bison</a>, implemented in JavaScript. It can recognize <a href="http://en.wikipedia.org/wiki/LR_grammar">LALR(1), LR(0), SLR(1), and LR(1)</a> type grammars. To create the Jison parser, we list the pattern to match on the left-hand side, and the action to take (usually the creation of syntax tree nodes) on the right. As the parser runs, it shifts tokens from our token stream, from left to right, and <a href="http://en.wikipedia.org/wiki/Bottom-up_parsing">attempts to match</a> the token sequence against the rules below. When a match can be made, it reduces into the <a href="http://en.wikipedia.org/wiki/Terminal_and_nonterminal_symbols">nonterminal</a> (the enclosing name at the top), and we proceed from there. </p> <p>If you run the <code>cake build:parser</code> command, Jison constructs a parse table from our rules and saves it into <code>lib/parser.js</code>. </p> </div> </li> <li id="section-2"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-2">¶</a> </div> <p>The only dependency is on the <strong>Jison.Parser</strong>. </p> </div> <div class="content"><div class='highlight'><pre>{Parser} = require <span class="string">'jison'</span></pre></div></div> </li> <li id="section-3"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-3">¶</a> </div> <h2>Jison DSL</h2> </div> </li> <li id="section-4"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-4">¶</a> </div> </div> </li> <li id="section-5"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-5">¶</a> </div> <p>Since we're going to be wrapped in a function by Jison in any case, if our action immediately returns a value, we can optimize by removing the function wrapper and just returning the value directly. </p> </div> <div class="content"><div class='highlight'><pre>unwrap = <span class="regexp">/^function\s*\(\)\s*\{\s*return\s*([\s\S]*);\s*\}/</span></pre></div></div> </li> <li id="section-6"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-6">¶</a> </div> <p>Our handy DSL for Jison grammar generation, thanks to <a href="http://github.com/creationix">Tim Caswell</a>. For every rule in the grammar, we pass the pattern-defining string, the action to run, and extra options, optionally. If no action is specified, we simply pass the value of the previous nonterminal. </p> </div> <div class="content"><div class='highlight'><pre><span class="function"><span class="title">o</span></span> = (patternString, action, options) -> patternString = patternString.replace <span class="regexp">/\s{2,}/g</span>, <span class="string">' '</span> patternCount = patternString.split(<span class="string">' '</span>).length <span class="keyword">return</span> [patternString, <span class="string">'$$ = $1;'</span>, options] <span class="keyword">unless</span> action action = <span class="keyword">if</span> match = unwrap.exec action <span class="keyword">then</span> match[<span class="number">1</span>] <span class="keyword">else</span> <span class="string">"(<span class="subst">#{action}</span>())"</span></pre></div></div> </li> <li id="section-7"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-7">¶</a> </div> <p>All runtime functions we need are defined on "yy" </p> </div> <div class="content"><div class='highlight'><pre> action = action.replace <span class="regexp">/\bnew /g</span>, <span class="string">'$&yy.'</span> action = action.replace <span class="regexp">/\b(?:Block\.wrap|extend)\b/g</span>, <span class="string">'yy.$&'</span></pre></div></div> </li> <li id="section-8"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-8">¶</a> </div> <p>Returns a function which adds location data to the first parameter passed in, and returns the parameter. If the parameter is not a node, it will just be passed through unaffected. </p> </div> <div class="content"><div class='highlight'><pre> <span class="function"><span class="title">addLocationDataFn</span></span> = (first, last) -> <span class="keyword">if</span> <span class="keyword">not</span> last <span class="string">"yy.addLocationDataFn(@<span class="subst">#{first}</span>)"</span> <span class="keyword">else</span> <span class="string">"yy.addLocationDataFn(@<span class="subst">#{first}</span>, @<span class="subst">#{last}</span>)"</span> action = action.replace <span class="regexp">/LOC\(([0-9]*)\)/g</span>, addLocationDataFn(<span class="string">'$1'</span>) action = action.replace <span class="regexp">/LOC\(([0-9]*),\s*([0-9]*)\)/g</span>, addLocationDataFn(<span class="string">'$1'</span>, <span class="string">'$2'</span>) [patternString, <span class="string">"$$ = <span class="subst">#{addLocationDataFn(<span class="number">1</span>, patternCount)}</span>(<span class="subst">#{action}</span>);"</span>, options]</pre></div></div> </li> <li id="section-9"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-9">¶</a> </div> <h2>Grammatical Rules</h2> </div> </li> <li id="section-10"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-10">¶</a> </div> </div> </li> <li id="section-11"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-11">¶</a> </div> <p>In all of the rules that follow, you'll see the name of the nonterminal as the key to a list of alternative matches. With each match's action, the dollar-sign variables are provided by Jison as references to the value of their numeric position, so in this rule: </p> <pre><code>"Expression UNLESS Expression"</code></pre> <p><code>$1</code> would be the value of the first <code>Expression</code>, <code>$2</code> would be the token for the <code>UNLESS</code> terminal, and <code>$3</code> would be the value of the second <code>Expression</code>. </p> </div> <div class="content"><div class='highlight'><pre>grammar =</pre></div></div> </li> <li id="section-12"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-12">¶</a> </div> <p>The <strong>Root</strong> is the top-level node in the syntax tree. Since we parse bottom-up, all parsing must end here. </p> </div> <div class="content"><div class='highlight'><pre> Root: [ o <span class="string">''</span>, -> <span class="keyword">new</span> Block o <span class="string">'Body'</span> o <span class="string">'Block TERMINATOR'</span> ]</pre></div></div> </li> <li id="section-13"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-13">¶</a> </div> <p>Any list of statements and expressions, separated by line breaks or semicolons. </p> </div> <div class="content"><div class='highlight'><pre> Body: [ o <span class="string">'Line'</span>, -> Block.wrap [$<span class="number">1</span>] o <span class="string">'Body TERMINATOR Line'</span>, -> $<span class="number">1.</span>push $<span class="number">3</span> o <span class="string">'Body TERMINATOR'</span> ]</pre></div></div> </li> <li id="section-14"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-14">¶</a> </div> <p>Block and statements, which make up a line in a body. </p> </div> <div class="content"><div class='highlight'><pre> Line: [ o <span class="string">'Expression'</span> o <span class="string">'Statement'</span> ]</pre></div></div> </li> <li id="section-15"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-15">¶</a> </div> <p>Pure statements which cannot be expressions. </p> </div> <div class="content"><div class='highlight'><pre> Statement: [ o <span class="string">'Return'</span> o <span class="string">'Comment'</span> o <span class="string">'STATEMENT'</span>, -> <span class="keyword">new</span> Literal $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-16"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-16">¶</a> </div> <p>All the different types of expressions in our language. The basic unit of CoffeeScript is the <strong>Expression</strong> -- everything that can be an expression is one. Blocks serve as the building blocks of many other rules, making them somewhat circular. </p> </div> <div class="content"><div class='highlight'><pre> Expression: [ o <span class="string">'Value'</span> o <span class="string">'Invocation'</span> o <span class="string">'Code'</span> o <span class="string">'Operation'</span> o <span class="string">'Assign'</span> o <span class="string">'If'</span> o <span class="string">'Try'</span> o <span class="string">'While'</span> o <span class="string">'For'</span> o <span class="string">'Switch'</span> o <span class="string">'Class'</span> o <span class="string">'Throw'</span> ]</pre></div></div> </li> <li id="section-17"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-17">¶</a> </div> <p>An indented block of expressions. Note that the <a href="rewriter.html">Rewriter</a> will convert some postfix forms into blocks for us, by adjusting the token stream. </p> </div> <div class="content"><div class='highlight'><pre> Block: [ o <span class="string">'INDENT OUTDENT'</span>, -> <span class="keyword">new</span> Block o <span class="string">'INDENT Body OUTDENT'</span>, -> $<span class="number">2</span> ]</pre></div></div> </li> <li id="section-18"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-18">¶</a> </div> <p>A literal identifier, a variable name or property. </p> </div> <div class="content"><div class='highlight'><pre> Identifier: [ o <span class="string">'IDENTIFIER'</span>, -> <span class="keyword">new</span> Literal $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-19"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-19">¶</a> </div> <p>Alphanumerics are separated from the other <strong>Literal</strong> matchers because they can also serve as keys in object literals. </p> </div> <div class="content"><div class='highlight'><pre> AlphaNumeric: [ o <span class="string">'NUMBER'</span>, -> <span class="keyword">new</span> Literal $<span class="number">1</span> o <span class="string">'STRING'</span>, -> <span class="keyword">new</span> Literal $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-20"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-20">¶</a> </div> <p>All of our immediate values. Generally these can be passed straight through and printed to JavaScript. </p> </div> <div class="content"><div class='highlight'><pre> Literal: [ o <span class="string">'AlphaNumeric'</span> o <span class="string">'JS'</span>, -> <span class="keyword">new</span> Literal $<span class="number">1</span> o <span class="string">'REGEX'</span>, -> <span class="keyword">new</span> Literal $<span class="number">1</span> o <span class="string">'DEBUGGER'</span>, -> <span class="keyword">new</span> Literal $<span class="number">1</span> o <span class="string">'UNDEFINED'</span>, -> <span class="keyword">new</span> Undefined o <span class="string">'NULL'</span>, -> <span class="keyword">new</span> Null o <span class="string">'BOOL'</span>, -> <span class="keyword">new</span> Bool $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-21"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-21">¶</a> </div> <p>Assignment of a variable, property, or index to a value. </p> </div> <div class="content"><div class='highlight'><pre> Assign: [ o <span class="string">'Assignable = Expression'</span>, -> <span class="keyword">new</span> Assign $<span class="number">1</span>, $<span class="number">3</span> o <span class="string">'Assignable = TERMINATOR Expression'</span>, -> <span class="keyword">new</span> Assign $<span class="number">1</span>, $<span class="number">4</span> o <span class="string">'Assignable = INDENT Expression OUTDENT'</span>, -> <span class="keyword">new</span> Assign $<span class="number">1</span>, $<span class="number">4</span> ]</pre></div></div> </li> <li id="section-22"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-22">¶</a> </div> <p>Assignment when it happens within an object literal. The difference from the ordinary <strong>Assign</strong> is that these allow numbers and strings as keys. </p> </div> <div class="content"><div class='highlight'><pre> AssignObj: [ o 'ObjAssignable', -> new Value $1 o 'ObjAssignable : Expression', -> new Assign LOC(1)(new Value($1)), $3, 'object' o 'ObjAssignable : INDENT Expression OUTDENT', -> new Assign LOC(1)(new Value($1)), $4, 'object' o 'Comment' ] ObjAssignable: [ o 'Identifier' o 'AlphaNumeric' o 'ThisProperty' ]</pre></div></div> </li> <li id="section-23"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-23">¶</a> </div> <p>A return statement from a function body. </p> </div> <div class="content"><div class='highlight'><pre> Return: [ o <span class="string">'RETURN Expression'</span>, -> <span class="keyword">new</span> Return $<span class="number">2</span> o <span class="string">'RETURN'</span>, -> <span class="keyword">new</span> Return ]</pre></div></div> </li> <li id="section-24"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-24">¶</a> </div> <p>A block comment. </p> </div> <div class="content"><div class='highlight'><pre> Comment: [ o <span class="string">'HERECOMMENT'</span>, -> <span class="keyword">new</span> Comment $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-25"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-25">¶</a> </div> <p>The <strong>Code</strong> node is the function literal. It's defined by an indented block of <strong>Block</strong> preceded by a function arrow, with an optional parameter list. </p> </div> <div class="content"><div class='highlight'><pre> Code: [ o <span class="string">'PARAM_START ParamList PARAM_END FuncGlyph Block'</span>, -> <span class="keyword">new</span> Code $<span class="number">2</span>, $<span class="number">5</span>, $<span class="number">4</span> o <span class="string">'FuncGlyph Block'</span>, -> <span class="keyword">new</span> Code [], $<span class="number">2</span>, $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-26"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-26">¶</a> </div> <p>CoffeeScript has two different symbols for functions. <code>-></code> is for ordinary functions, and <code>=></code> is for functions bound to the current value of <em>this</em>. </p> </div> <div class="content"><div class='highlight'><pre> FuncGlyph: [ o <span class="string">'->'</span>, -> <span class="string">'func'</span> o <span class="string">'=>'</span>, -> <span class="string">'boundfunc'</span> ]</pre></div></div> </li> <li id="section-27"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-27">¶</a> </div> <p>An optional, trailing comma. </p> </div> <div class="content"><div class='highlight'><pre> OptComma: [ o <span class="string">''</span> o <span class="string">','</span> ]</pre></div></div> </li> <li id="section-28"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-28">¶</a> </div> <p>The list of parameters that a function accepts can be of any length. </p> </div> <div class="content"><div class='highlight'><pre> ParamList: [ o <span class="string">''</span>, -> [] o <span class="string">'Param'</span>, -> [$<span class="number">1</span>] o <span class="string">'ParamList , Param'</span>, -> $<span class="number">1.</span>concat $<span class="number">3</span> o <span class="string">'ParamList OptComma TERMINATOR Param'</span>, -> $<span class="number">1.</span>concat $<span class="number">4</span> o <span class="string">'ParamList OptComma INDENT ParamList OptComma OUTDENT'</span>, -> $<span class="number">1.</span>concat $<span class="number">4</span> ]</pre></div></div> </li> <li id="section-29"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-29">¶</a> </div> <p>A single parameter in a function definition can be ordinary, or a splat that hoovers up the remaining arguments. </p> </div> <div class="content"><div class='highlight'><pre> Param: [ o <span class="string">'ParamVar'</span>, -> <span class="keyword">new</span> Param $<span class="number">1</span> o <span class="string">'ParamVar ...'</span>, -> <span class="keyword">new</span> Param $<span class="number">1</span>, <span class="literal">null</span>, <span class="literal">on</span> o <span class="string">'ParamVar = Expression'</span>, -> <span class="keyword">new</span> Param $<span class="number">1</span>, $<span class="number">3</span> ]</pre></div></div> </li> <li id="section-30"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-30">¶</a> </div> <p>Function Parameters </p> </div> <div class="content"><div class='highlight'><pre> ParamVar: [ o <span class="string">'Identifier'</span> o <span class="string">'ThisProperty'</span> o <span class="string">'Array'</span> o <span class="string">'Object'</span> ]</pre></div></div> </li> <li id="section-31"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-31">¶</a> </div> <p>A splat that occurs outside of a parameter list. </p> </div> <div class="content"><div class='highlight'><pre> Splat: [ o <span class="string">'Expression ...'</span>, -> <span class="keyword">new</span> Splat $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-32"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-32">¶</a> </div> <p>Variables and properties that can be assigned to. </p> </div> <div class="content"><div class='highlight'><pre> SimpleAssignable: [ o <span class="string">'Identifier'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span> o <span class="string">'Value Accessor'</span>, -> $<span class="number">1.</span>add $<span class="number">2</span> o <span class="string">'Invocation Accessor'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span>, [].concat $<span class="number">2</span> o <span class="string">'ThisProperty'</span> ]</pre></div></div> </li> <li id="section-33"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-33">¶</a> </div> <p>Everything that can be assigned to. </p> </div> <div class="content"><div class='highlight'><pre> Assignable: [ o <span class="string">'SimpleAssignable'</span> o <span class="string">'Array'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span> o <span class="string">'Object'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-34"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-34">¶</a> </div> <p>The types of things that can be treated as values -- assigned to, invoked as functions, indexed into, named as a class, etc. </p> </div> <div class="content"><div class='highlight'><pre> Value: [ o <span class="string">'Assignable'</span> o <span class="string">'Literal'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span> o <span class="string">'Parenthetical'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span> o <span class="string">'Range'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span> o <span class="string">'This'</span> ]</pre></div></div> </li> <li id="section-35"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-35">¶</a> </div> <p>The general group of accessors into an object, by property, by prototype or by array index or slice. </p> </div> <div class="content"><div class='highlight'><pre> Accessor: [ o <span class="string">'. Identifier'</span>, -> <span class="keyword">new</span> Access $<span class="number">2</span> o <span class="string">'?. Identifier'</span>, -> <span class="keyword">new</span> Access $<span class="number">2</span>, <span class="string">'soak'</span> o <span class="string">':: Identifier'</span>, -> [LOC(<span class="number">1</span>)(<span class="keyword">new</span> Access <span class="keyword">new</span> Literal(<span class="string">'prototype'</span>)), LOC(<span class="number">2</span>)(<span class="keyword">new</span> Access $<span class="number">2</span>)] o <span class="string">'?:: Identifier'</span>, -> [LOC(<span class="number">1</span>)(<span class="keyword">new</span> Access <span class="keyword">new</span> Literal(<span class="string">'prototype'</span>), <span class="string">'soak'</span>), LOC(<span class="number">2</span>)(<span class="keyword">new</span> Access $<span class="number">2</span>)] o <span class="string">'::'</span>, -> <span class="keyword">new</span> Access <span class="keyword">new</span> Literal <span class="string">'prototype'</span> o <span class="string">'Index'</span> ]</pre></div></div> </li> <li id="section-36"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-36">¶</a> </div> <p>Indexing into an object or array using bracket notation. </p> </div> <div class="content"><div class='highlight'><pre> Index: [ o <span class="string">'INDEX_START IndexValue INDEX_END'</span>, -> $<span class="number">2</span> o <span class="string">'INDEX_SOAK Index'</span>, -> extend $<span class="number">2</span>, soak : <span class="literal">yes</span> ] IndexValue: [ o <span class="string">'Expression'</span>, -> <span class="keyword">new</span> Index $<span class="number">1</span> o <span class="string">'Slice'</span>, -> <span class="keyword">new</span> Slice $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-37"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-37">¶</a> </div> <p>In CoffeeScript, an object literal is simply a list of assignments. </p> </div> <div class="content"><div class='highlight'><pre> Object: [ o <span class="string">'{ AssignList OptComma }'</span>, -> <span class="keyword">new</span> Obj $<span class="number">2</span>, $<span class="number">1.</span>generated ]</pre></div></div> </li> <li id="section-38"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-38">¶</a> </div> <p>Assignment of properties within an object literal can be separated by comma, as in JavaScript, or simply by newline. </p> </div> <div class="content"><div class='highlight'><pre> AssignList: [ o <span class="string">''</span>, -> [] o <span class="string">'AssignObj'</span>, -> [$<span class="number">1</span>] o <span class="string">'AssignList , AssignObj'</span>, -> $<span class="number">1.</span>concat $<span class="number">3</span> o <span class="string">'AssignList OptComma TERMINATOR AssignObj'</span>, -> $<span class="number">1.</span>concat $<span class="number">4</span> o <span class="string">'AssignList OptComma INDENT AssignList OptComma OUTDENT'</span>, -> $<span class="number">1.</span>concat $<span class="number">4</span> ]</pre></div></div> </li> <li id="section-39"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-39">¶</a> </div> <p>Class definitions have optional bodies of prototype property assignments, and optional references to the superclass. </p> </div> <div class="content"><div class='highlight'><pre> Class: [ o <span class="string">'CLASS'</span>, -> <span class="keyword">new</span> Class o <span class="string">'CLASS Block'</span>, -> <span class="keyword">new</span> Class <span class="literal">null</span>, <span class="literal">null</span>, $<span class="number">2</span> o <span class="string">'CLASS EXTENDS Expression'</span>, -> <span class="keyword">new</span> Class <span class="literal">null</span>, $<span class="number">3</span> o <span class="string">'CLASS EXTENDS Expression Block'</span>, -> <span class="keyword">new</span> Class <span class="literal">null</span>, $<span class="number">3</span>, $<span class="number">4</span> o <span class="string">'CLASS SimpleAssignable'</span>, -> <span class="keyword">new</span> Class $<span class="number">2</span> o <span class="string">'CLASS SimpleAssignable Block'</span>, -> <span class="keyword">new</span> Class $<span class="number">2</span>, <span class="literal">null</span>, $<span class="number">3</span> o <span class="string">'CLASS SimpleAssignable EXTENDS Expression'</span>, -> <span class="keyword">new</span> Class $<span class="number">2</span>, $<span class="number">4</span> o <span class="string">'CLASS SimpleAssignable EXTENDS Expression Block'</span>, -> <span class="keyword">new</span> Class $<span class="number">2</span>, $<span class="number">4</span>, $<span class="number">5</span> ]</pre></div></div> </li> <li id="section-40"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-40">¶</a> </div> <p>Ordinary function invocation, or a chained series of calls. </p> </div> <div class="content"><div class='highlight'><pre> Invocation: [ o <span class="string">'Value OptFuncExist Arguments'</span>, -> <span class="keyword">new</span> Call $<span class="number">1</span>, $<span class="number">3</span>, $<span class="number">2</span> o <span class="string">'Invocation OptFuncExist Arguments'</span>, -> <span class="keyword">new</span> Call $<span class="number">1</span>, $<span class="number">3</span>, $<span class="number">2</span> o <span class="string">'SUPER'</span>, -> <span class="keyword">new</span> Call <span class="string">'super'</span>, [<span class="keyword">new</span> Splat <span class="keyword">new</span> Literal <span class="string">'arguments'</span>] o <span class="string">'SUPER Arguments'</span>, -> <span class="keyword">new</span> Call <span class="string">'super'</span>, $<span class="number">2</span> ]</pre></div></div> </li> <li id="section-41"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-41">¶</a> </div> <p>An optional existence check on a function. </p> </div> <div class="content"><div class='highlight'><pre> OptFuncExist: [ o <span class="string">''</span>, -> <span class="literal">no</span> o <span class="string">'FUNC_EXIST'</span>, -> <span class="literal">yes</span> ]</pre></div></div> </li> <li id="section-42"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-42">¶</a> </div> <p>The list of arguments to a function call. </p> </div> <div class="content"><div class='highlight'><pre> Arguments: [ o <span class="string">'CALL_START CALL_END'</span>, -> [] o <span class="string">'CALL_START ArgList OptComma CALL_END'</span>, -> $<span class="number">2</span> ]</pre></div></div> </li> <li id="section-43"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-43">¶</a> </div> <p>A reference to the <em>this</em> current object. </p> </div> <div class="content"><div class='highlight'><pre> This: [ o <span class="string">'THIS'</span>, -> <span class="keyword">new</span> Value <span class="keyword">new</span> Literal <span class="string">'this'</span> o <span class="string">'@'</span>, -> <span class="keyword">new</span> Value <span class="keyword">new</span> Literal <span class="string">'this'</span> ]</pre></div></div> </li> <li id="section-44"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-44">¶</a> </div> <p>A reference to a property on <em>this</em>. </p> </div> <div class="content"><div class='highlight'><pre> ThisProperty: [ o <span class="string">'@ Identifier'</span>, -> <span class="keyword">new</span> Value LOC(<span class="number">1</span>)(<span class="keyword">new</span> Literal(<span class="string">'this'</span>)), [LOC(<span class="number">2</span>)(<span class="keyword">new</span> Access($<span class="number">2</span>))], <span class="string">'this'</span> ]</pre></div></div> </li> <li id="section-45"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-45">¶</a> </div> <p>The array literal. </p> </div> <div class="content"><div class='highlight'><pre> Array: [ o <span class="string">'[ ]'</span>, -> <span class="keyword">new</span> Arr [] o <span class="string">'[ ArgList OptComma ]'</span>, -> <span class="keyword">new</span> Arr $<span class="number">2</span> ]</pre></div></div> </li> <li id="section-46"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-46">¶</a> </div> <p>Inclusive and exclusive range dots. </p> </div> <div class="content"><div class='highlight'><pre> RangeDots: [ o <span class="string">'..'</span>, -> <span class="string">'inclusive'</span> o <span class="string">'...'</span>, -> <span class="string">'exclusive'</span> ]</pre></div></div> </li> <li id="section-47"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-47">¶</a> </div> <p>The CoffeeScript range literal. </p> </div> <div class="content"><div class='highlight'><pre> Range: [ o <span class="string">'[ Expression RangeDots Expression ]'</span>, -> <span class="keyword">new</span> Range $<span class="number">2</span>, $<span class="number">4</span>, $<span class="number">3</span> ]</pre></div></div> </li> <li id="section-48"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-48">¶</a> </div> <p>Array slice literals. </p> </div> <div class="content"><div class='highlight'><pre> Slice: [ o <span class="string">'Expression RangeDots Expression'</span>, -> <span class="keyword">new</span> Range $<span class="number">1</span>, $<span class="number">3</span>, $<span class="number">2</span> o <span class="string">'Expression RangeDots'</span>, -> <span class="keyword">new</span> Range $<span class="number">1</span>, <span class="literal">null</span>, $<span class="number">2</span> o <span class="string">'RangeDots Expression'</span>, -> <span class="keyword">new</span> Range <span class="literal">null</span>, $<span class="number">2</span>, $<span class="number">1</span> o <span class="string">'RangeDots'</span>, -> <span class="keyword">new</span> Range <span class="literal">null</span>, <span class="literal">null</span>, $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-49"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-49">¶</a> </div> <p>The <strong>ArgList</strong> is both the list of objects passed into a function call, as well as the contents of an array literal (i.e. comma-separated expressions). Newlines work as well. </p> </div> <div class="content"><div class='highlight'><pre> ArgList: [ o <span class="string">'Arg'</span>, -> [$<span class="number">1</span>] o <span class="string">'ArgList , Arg'</span>, -> $<span class="number">1.</span>concat $<span class="number">3</span> o <span class="string">'ArgList OptComma TERMINATOR Arg'</span>, -> $<span class="number">1.</span>concat $<span class="number">4</span> o <span class="string">'INDENT ArgList OptComma OUTDENT'</span>, -> $<span class="number">2</span> o <span class="string">'ArgList OptComma INDENT ArgList OptComma OUTDENT'</span>, -> $<span class="number">1.</span>concat $<span class="number">4</span> ]</pre></div></div> </li> <li id="section-50"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-50">¶</a> </div> <p>Valid arguments are Blocks or Splats. </p> </div> <div class="content"><div class='highlight'><pre> Arg: [ o <span class="string">'Expression'</span> o <span class="string">'Splat'</span> ]</pre></div></div> </li> <li id="section-51"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-51">¶</a> </div> <p>Just simple, comma-separated, required arguments (no fancy syntax). We need this to be separate from the <strong>ArgList</strong> for use in <strong>Switch</strong> blocks, where having the newlines wouldn't make sense. </p> </div> <div class="content"><div class='highlight'><pre> SimpleArgs: [ o <span class="string">'Expression'</span> o <span class="string">'SimpleArgs , Expression'</span>, -> [].concat $<span class="number">1</span>, $<span class="number">3</span> ]</pre></div></div> </li> <li id="section-52"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-52">¶</a> </div> <p>The variants of <em>try/catch/finally</em> exception handling blocks. </p> </div> <div class="content"><div class='highlight'><pre> Try: [ o <span class="string">'TRY Block'</span>, -> <span class="keyword">new</span> Try $<span class="number">2</span> o <span class="string">'TRY Block Catch'</span>, -> <span class="keyword">new</span> Try $<span class="number">2</span>, $<span class="number">3</span>[<span class="number">0</span>], $<span class="number">3</span>[<span class="number">1</span>] o <span class="string">'TRY Block FINALLY Block'</span>, -> <span class="keyword">new</span> Try $<span class="number">2</span>, <span class="literal">null</span>, <span class="literal">null</span>, $<span class="number">4</span> o <span class="string">'TRY Block Catch FINALLY Block'</span>, -> <span class="keyword">new</span> Try $<span class="number">2</span>, $<span class="number">3</span>[<span class="number">0</span>], $<span class="number">3</span>[<span class="number">1</span>], $<span class="number">5</span> ]</pre></div></div> </li> <li id="section-53"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-53">¶</a> </div> <p>A catch clause names its error and runs a block of code. </p> </div> <div class="content"><div class='highlight'><pre> Catch: [ o <span class="string">'CATCH Identifier Block'</span>, -> [$<span class="number">2</span>, $<span class="number">3</span>] o <span class="string">'CATCH Object Block'</span>, -> [LOC(<span class="number">2</span>)(<span class="keyword">new</span> Value($<span class="number">2</span>)), $<span class="number">3</span>] o <span class="string">'CATCH Block'</span>, -> [<span class="literal">null</span>, $<span class="number">2</span>] ]</pre></div></div> </li> <li id="section-54"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-54">¶</a> </div> <p>Throw an exception object. </p> </div> <div class="content"><div class='highlight'><pre> Throw: [ o <span class="string">'THROW Expression'</span>, -> <span class="keyword">new</span> Throw $<span class="number">2</span> ]</pre></div></div> </li> <li id="section-55"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-55">¶</a> </div> <p>Parenthetical expressions. Note that the <strong>Parenthetical</strong> is a <strong>Value</strong>, not an <strong>Expression</strong>, so if you need to use an expression in a place where only values are accepted, wrapping it in parentheses will always do the trick. </p> </div> <div class="content"><div class='highlight'><pre> Parenthetical: [ o <span class="string">'( Body )'</span>, -> <span class="keyword">new</span> Parens $<span class="number">2</span> o <span class="string">'( INDENT Body OUTDENT )'</span>, -> <span class="keyword">new</span> Parens $<span class="number">3</span> ]</pre></div></div> </li> <li id="section-56"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-56">¶</a> </div> <p>The condition portion of a while loop. </p> </div> <div class="content"><div class='highlight'><pre> WhileSource: [ o <span class="string">'WHILE Expression'</span>, -> <span class="keyword">new</span> While $<span class="number">2</span> o <span class="string">'WHILE Expression WHEN Expression'</span>, -> <span class="keyword">new</span> While $<span class="number">2</span>, guard: $<span class="number">4</span> o <span class="string">'UNTIL Expression'</span>, -> <span class="keyword">new</span> While $<span class="number">2</span>, invert: <span class="literal">true</span> o <span class="string">'UNTIL Expression WHEN Expression'</span>, -> <span class="keyword">new</span> While $<span class="number">2</span>, invert: <span class="literal">true</span>, guard: $<span class="number">4</span> ]</pre></div></div> </li> <li id="section-57"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-57">¶</a> </div> <p>The while loop can either be normal, with a block of expressions to execute, or postfix, with a single expression. There is no do..while. </p> </div> <div class="content"><div class='highlight'><pre> While: [ o <span class="string">'WhileSource Block'</span>, -> $<span class="number">1.</span>addBody $<span class="number">2</span> o <span class="string">'Statement WhileSource'</span>, -> $<span class="number">2.</span>addBody LOC(<span class="number">1</span>) Block.wrap([$<span class="number">1</span>]) o <span class="string">'Expression WhileSource'</span>, -> $<span class="number">2.</span>addBody LOC(<span class="number">1</span>) Block.wrap([$<span class="number">1</span>]) o <span class="string">'Loop'</span>, -> $<span class="number">1</span> ] Loop: [ o <span class="string">'LOOP Block'</span>, -> <span class="keyword">new</span> While(LOC(<span class="number">1</span>) <span class="keyword">new</span> Literal <span class="string">'true'</span>).addBody $<span class="number">2</span> o <span class="string">'LOOP Expression'</span>, -> <span class="keyword">new</span> While(LOC(<span class="number">1</span>) <span class="keyword">new</span> Literal <span class="string">'true'</span>).addBody LOC(<span class="number">2</span>) Block.wrap [$<span class="number">2</span>] ]</pre></div></div> </li> <li id="section-58"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-58">¶</a> </div> <p>Array, object, and range comprehensions, at the most generic level. Comprehensions can either be normal, with a block of expressions to execute, or postfix, with a single expression. </p> </div> <div class="content"><div class='highlight'><pre> For: [ o <span class="string">'Statement ForBody'</span>, -> <span class="keyword">new</span> For $<span class="number">1</span>, $<span class="number">2</span> o <span class="string">'Expression ForBody'</span>, -> <span class="keyword">new</span> For $<span class="number">1</span>, $<span class="number">2</span> o <span class="string">'ForBody Block'</span>, -> <span class="keyword">new</span> For $<span class="number">2</span>, $<span class="number">1</span> ] ForBody: [ o <span class="string">'FOR Range'</span>, -> source: LOC(<span class="number">2</span>) <span class="keyword">new</span> Value($<span class="number">2</span>) o <span class="string">'ForStart ForSource'</span>, -> $<span class="number">2.</span>own = $<span class="number">1.</span>own; $<span class="number">2.</span>name = $<span class="number">1</span>[<span class="number">0</span>]; $<span class="number">2.</span>index = $<span class="number">1</span>[<span class="number">1</span>]; $<span class="number">2</span> ] ForStart: [ o <span class="string">'FOR ForVariables'</span>, -> $<span class="number">2</span> o <span class="string">'FOR OWN ForVariables'</span>, -> $<span class="number">3.</span>own = <span class="literal">yes</span>; $<span class="number">3</span> ]</pre></div></div> </li> <li id="section-59"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-59">¶</a> </div> <p>An array of all accepted values for a variable inside the loop. This enables support for pattern matching. </p> </div> <div class="content"><div class='highlight'><pre> ForValue: [ o <span class="string">'Identifier'</span> o <span class="string">'ThisProperty'</span> o <span class="string">'Array'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span> o <span class="string">'Object'</span>, -> <span class="keyword">new</span> Value $<span class="number">1</span> ]</pre></div></div> </li> <li id="section-60"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-60">¶</a> </div> <p>An array or range comprehension has variables for the current element and (optional) reference to the current index. Or, <em>key, value</em>, in the case of object comprehensions. </p> </div> <div class="content"><div class='highlight'><pre> ForVariables: [ o <span class="string">'ForValue'</span>, -> [$<span class="number">1</span>] o <span class="string">'ForValue , ForValue'</span>, -> [$<span class="number">1</span>, $<span class="number">3</span>] ]</pre></div></div> </li> <li id="section-61"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-61">¶</a> </div> <p>The source of a comprehension is an array or object with an optional guard clause. If it's an array comprehension, you can also choose to step through in fixed-size increments. </p> </div> <div class="content"><div class='highlight'><pre> ForSource: [ o <span class="string">'FORIN Expression'</span>, -> source: $<span class="number">2</span> o <span class="string">'FOROF Expression'</span>, -> source: $<span class="number">2</span>, object: <span class="literal">yes</span> o <span class="string">'FORIN Expression WHEN Expression'</span>, -> source: $<span class="number">2</span>, guard: $<span class="number">4</span> o <span class="string">'FOROF Expression WHEN Expression'</span>, -> source: $<span class="number">2</span>, guard: $<span class="number">4</span>, object: <span class="literal">yes</span> o <span class="string">'FORIN Expression BY Expression'</span>, -> source: $<span class="number">2</span>, step: $<span class="number">4</span> o <span class="string">'FORIN Expression WHEN Expression BY Expression'</span>, -> source: $<span class="number">2</span>, guard: $<span class="number">4</span>, step: $<span class="number">6</span> o <span class="string">'FORIN Expression BY Expression WHEN Expression'</span>, -> source: $<span class="number">2</span>, step: $<span class="number">4</span>, guard: $<span class="number">6</span> ] Switch: [ o <span class="string">'SWITCH Expression INDENT Whens OUTDENT'</span>, -> <span class="keyword">new</span> Switch $<span class="number">2</span>, $<span class="number">4</span> o <span class="string">'SWITCH Expression INDENT Whens ELSE Block OUTDENT'</span>, -> <span class="keyword">new</span> Switch $<span class="number">2</span>, $<span class="number">4</span>, $<span class="number">6</span> o <span class="string">'SWITCH INDENT Whens OUTDENT'</span>, -> <span class="keyword">new</span> Switch <span class="literal">null</span>, $<span class="number">3</span> o <span class="string">'SWITCH INDENT Whens ELSE Block OUTDENT'</span>, -> <span class="keyword">new</span> Switch <span class="literal">null</span>, $<span class="number">3</span>, $<span class="number">5</span> ] Whens: [ o <span class="string">'When'</span> o <span class="string">'Whens When'</span>, -> $<span class="number">1.</span>concat $<span class="number">2</span> ]</pre></div></div> </li> <li id="section-62"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-62">¶</a> </div> <p>An individual <strong>When</strong> clause, with action. </p> </div> <div class="content"><div class='highlight'><pre> When: [ o <span class="string">'LEADING_WHEN SimpleArgs Block'</span>, -> [[$<span class="number">2</span>, $<span class="number">3</span>]] o <span class="string">'LEADING_WHEN SimpleArgs Block TERMINATOR'</span>, -> [[$<span class="number">2</span>, $<span class="number">3</span>]] ]</pre></div></div> </li> <li id="section-63"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-63">¶</a> </div> <p>The most basic form of <em>if</em> is a condition and an action. The following if-related rules are broken up along these lines in order to avoid ambiguity. </p> </div> <div class="content"><div class='highlight'><pre> IfBlock: [ o <span class="string">'IF Expression Block'</span>, -> <span class="keyword">new</span> If $<span class="number">2</span>, $<span class="number">3</span>, type: $<span class="number">1</span> o <span class="string">'IfBlock ELSE IF Expression Block'</span>, -> $<span class="number">1.</span>addElse <span class="keyword">new</span> If $<span class="number">4</span>, $<span class="number">5</span>, type: $<span class="number">3</span> ]</pre></div></div> </li> <li id="section-64"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-64">¶</a> </div> <p>The full complement of <em>if</em> expressions, including postfix one-liner <em>if</em> and <em>unless</em>. </p> </div> <div class="content"><div class='highlight'><pre> If: [ o <span class="string">'IfBlock'</span> o <span class="string">'IfBlock ELSE Block'</span>, -> $<span class="number">1.</span>addElse $<span class="number">3</span> o <span class="string">'Statement POST_IF Expression'</span>, -> <span class="keyword">new</span> If $<span class="number">3</span>, LOC(<span class="number">1</span>)(Block.wrap [$<span class="number">1</span>]), type: $<span class="number">2</span>, statement: <span class="literal">true</span> o <span class="string">'Expression POST_IF Expression'</span>, -> <span class="keyword">new</span> If $<span class="number">3</span>, LOC(<span class="number">1</span>)(Block.wrap [$<span class="number">1</span>]), type: $<span class="number">2</span>, statement: <span class="literal">true</span> ]</pre></div></div> </li> <li id="section-65"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-65">¶</a> </div> <p>Arithmetic and logical operators, working on one or more operands. Here they are grouped by order of precedence. The actual precedence rules are defined at the bottom of the page. It would be shorter if we could combine most of these rules into a single generic <em>Operand OpSymbol Operand</em> -type rule, but in order to make the precedence binding possible, separate rules are necessary. </p> </div> <div class="content"><div class='highlight'><pre> Operation: [ o <span class="string">'UNARY Expression'</span>, -> <span class="keyword">new</span> Op $<span class="number">1</span> , $<span class="number">2</span> o <span class="string">'- Expression'</span>, (-> <span class="keyword">new</span> Op <span class="string">'-'</span>, $<span class="number">2</span>), prec: <span class="string">'UNARY'</span> o <span class="string">'+ Expression'</span>, (-> <span class="keyword">new</span> Op <span class="string">'+'</span>, $<span class="number">2</span>), prec: <span class="string">'UNARY'</span> o <span class="string">'-- SimpleAssignable'</span>, -> <span class="keyword">new</span> Op <span class="string">'--'</span>, $<span class="number">2</span> o <span class="string">'++ SimpleAssignable'</span>, -> <span class="keyword">new</span> Op <span class="string">'++'</span>, $<span class="number">2</span> o <span class="string">'SimpleAssignable --'</span>, -> <span class="keyword">new</span> Op <span class="string">'--'</span>, $<span class="number">1</span>, <span class="literal">null</span>, <span class="literal">true</span> o <span class="string">'SimpleAssignable ++'</span>, -> <span class="keyword">new</span> Op <span class="string">'++'</span>, $<span class="number">1</span>, <span class="literal">null</span>, <span class="literal">true</span></pre></div></div> </li> <li id="section-66"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-66">¶</a> </div> <p><a href="http://jashkenas.github.com/coffee-script/#existence">The existential operator</a>. </p> </div> <div class="content"><div class='highlight'><pre> o 'Expression ?', -> new Existence $1 o 'Expression + Expression', -> new Op '+' , $1, $3 o 'Expression - Expression', -> new Op '-' , $1, $3 o 'Expression MATH Expression', -> new Op $2, $1, $3 o 'Expression SHIFT Expression', -> new Op $2, $1, $3 o 'Expression COMPARE Expression', -> new Op $2, $1, $3 o 'Expression LOGIC Expression', -> new Op $2, $1, $3 o 'Expression RELATION Expression', -> if $2.charAt(0) is '!' new Op($2[1..], $1, $3).invert() else new Op $2, $1, $3 o 'SimpleAssignable COMPOUND_ASSIGN Expression', -> new Assign $1, $3, $2 o 'SimpleAssignable COMPOUND_ASSIGN INDENT Expression OUTDENT', -> new Assign $1, $4, $2 o 'SimpleAssignable COMPOUND_ASSIGN TERMINATOR Expression', -> new Assign $1, $4, $2 o 'SimpleAssignable EXTENDS Expression', -> new Extends $1, $3 ]</pre></div></div> </li> <li id="section-67"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-67">¶</a> </div> <h2>Precedence</h2> </div> </li> <li id="section-68"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-68">¶</a> </div> </div> </li> <li id="section-69"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-69">¶</a> </div> <p>Operators at the top of this list have higher precedence than the ones lower down. Following these rules is what makes <code>2 + 3 * 4</code> parse as: </p> <pre><code>2 + (3 * 4)</code></pre> <p>And not: </p> <pre><code>(2 + 3) * 4</code></pre> </div> <div class="content"><div class='highlight'><pre>operators = [ [<span class="string">'left'</span>, <span class="string">'.'</span>, <span class="string">'?.'</span>, <span class="string">'::'</span>, <span class="string">'?::'</span>] [<span class="string">'left'</span>, <span class="string">'CALL_START'</span>, <span class="string">'CALL_END'</span>] [<span class="string">'nonassoc'</span>, <span class="string">'++'</span>, <span class="string">'--'</span>] [<span class="string">'left'</span>, <span class="string">'?'</span>] [<span class="string">'right'</span>, <span class="string">'UNARY'</span>] [<span class="string">'left'</span>, <span class="string">'MATH'</span>] [<span class="string">'left'</span>, <span class="string">'+'</span>, <span class="string">'-'</span>] [<span class="string">'left'</span>, <span class="string">'SHIFT'</span>] [<span class="string">'left'</span>, <span class="string">'RELATION'</span>] [<span class="string">'left'</span>, <span class="string">'COMPARE'</span>] [<span class="string">'left'</span>, <span class="string">'LOGIC'</span>] [<span class="string">'nonassoc'</span>, <span class="string">'INDENT'</span>, <span class="string">'OUTDENT'</span>] [<span class="string">'right'</span>, <span class="string">'='</span>, <span class="string">':'</span>, <span class="string">'COMPOUND_ASSIGN'</span>, <span class="string">'RETURN'</span>, <span class="string">'THROW'</span>, <span class="string">'EXTENDS'</span>] [<span class="string">'right'</span>, <span class="string">'FORIN'</span>, <span class="string">'FOROF'</span>, <span class="string">'BY'</span>, <span class="string">'WHEN'</span>] [<span class="string">'right'</span>, <span class="string">'IF'</span>, <span class="string">'ELSE'</span>, <span class="string">'FOR'</span>, <span class="string">'WHILE'</span>, <span class="string">'UNTIL'</span>, <span class="string">'LOOP'</span>, <span class="string">'SUPER'</span>, <span class="string">'CLASS'</span>] [<span class="string">'right'</span>, <span class="string">'POST_IF'</span>] ]</pre></div></div> </li> <li id="section-70"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-70">¶</a> </div> <h2>Wrapping Up</h2> </div> </li> <li id="section-71"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-71">¶</a> </div> </div> </li> <li id="section-72"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-72">¶</a> </div> <p>Finally, now that we have our <strong>grammar</strong> and our <strong>operators</strong>, we can create our <strong>Jison.Parser</strong>. We do this by processing all of our rules, recording all terminals (every symbol which does not appear as the name of a rule above) as "tokens". </p> </div> <div class="content"><div class='highlight'><pre>tokens = [] <span class="keyword">for</span> name, alternatives <span class="keyword">of</span> grammar grammar[name] = <span class="keyword">for</span> alt <span class="keyword">in</span> alternatives <span class="keyword">for</span> token <span class="keyword">in</span> alt[<span class="number">0</span>].split <span class="string">' '</span> tokens.push token <span class="keyword">unless</span> grammar[token] alt[<span class="number">1</span>] = <span class="string">"return <span class="subst">#{alt[<span class="number">1</span>]}</span>"</span> <span class="keyword">if</span> name <span class="keyword">is</span> <span class="string">'Root'</span> alt</pre></div></div> </li> <li id="section-73"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-73">¶</a> </div> <p>Initialize the <strong>Parser</strong> with our list of terminal <strong>tokens</strong>, our <strong>grammar</strong> rules, and the name of the root. Reverse the operators because Jison orders precedence from low to high, and we have it high to low (as in <a href="http://dinosaur.compilertools.net/yacc/index.html">Yacc</a>). </p> </div> <div class="content"><div class='highlight'><pre>exports.parser = <span class="keyword">new</span> Parser tokens : tokens.join <span class="string">' '</span> bnf : grammar operators : operators.reverse() startSymbol : <span class="string">'Root'</span></pre></div></div> </li> </ul> </div> </body> </html>