typo3/sysext/t3editor/jslib/parsetyposcript.js

   1 /* TypoScript parser
   2  *
   3  * based on parsejavascript.js by Marijn Haverbeke
   4  *
   5  * A parser that can be plugged into the CodeMirror system has to
   6  * implement the following interface: It is a function that, when
   7  * called with a string stream (stringstream.js) as an argument,
   8  * returns a MochiKit-style iterator (object with a 'next' method).
   9  * This iterator, when called, consumes some input from the string
  10  * stream, and returns a token object. Token objects must have a
  11  * 'value' property (the text they represent), a 'style' property (the
  12  * CSS style that should be used to colour them). Tokens for newline
  13  * characters must also have a 'lexicalContext' property, which has an
  14  * 'indentation' method that can be used to determine the proper
  15  * indentation level for the next line. This method optionally takes
  16  * the first character of the next line as an argument, which it can
  17  * use to adjust the indentation level.
  18  *
  19  * So far this should be easy. The hard part is that the iterator
  20  * produced by the parse function must also have a 'copy' method. This
  21  * method, called without arguments, returns a function representing
  22  * the current state of the parser. When this function is later called
  23  * with a string stream as its argument, it returns a parser iterator
  24  * object that resumes parsing using the old state and the new input
  25  * stream. It may assume that only one parser is active at a time, and
  26  * clobber the state of the old parser (the implementation below
  27  * certianly does).
  28  */
  29
  30 // Parse function for TypoScript. Makes use of the tokenizer from
  31 // tokenizetyposcript.js. Note that your parsers do not have to be
  32 // this complicated -- if you don't want to recognize local variables,
  33 // in many languages it is enough to just look for braces, semicolons,
  34 // parentheses, etc, and know when you are inside a string or comment.
  35 var parseTypoScript = function() {
  36   // Token types that can be considered to be atoms.
  37   var atomicTypes = setObject("atom", "number", "variable", "string", "regexp");
  38
  39   // Constructor for the lexical context objects.
  40   function TSLexical(indented, column, type, align, prev) {
  41     // indentation at start of this line
  42     this.indented = indented;
  43     // column at which this scope was opened
  44     this.column = column;
  45     // type of scope ('vardef', 'stat' (statement), '[', '{', or '(')
  46     this.type = type;
  47     // '[', '{', or '(' blocks that have any text after their opening
  48     // character are said to be 'aligned' -- any lines below are
  49     // indented all the way to the opening character.
  50     if (align != null)
  51       this.align = align;
  52     // Parent scope, if any.
  53     this.prev = prev;
  54   }
  55   // My favourite indentation rules.
  56   TSLexical.prototype.indentation = function(firstChar) {
  57     var closing = firstChar == this.type;
  58         if (this.type == "}")
  59       return this.indented + 2;
  60
  61     else if (this.align)
  62       return this.column - (closing ? 1 : 0);
  63     else
  64       return this.indented + (closing ? 0 : 2);
  65   }
  66
  67   // The parser-iterator-producing function itself.
  68   return function(input){
  69     // Wrap the input in a token stream
  70     var tokens = tokenizeTypoScript(input);
  71     // The parser state. cc is a stack of actions that have to be
  72     // performed to finish the current statement. For example we might
  73     // know that we still need to find a closing parenthesis and a
  74     // semicolon. Actions at the end of the stack go first. It is
  75     // initialized with an infinitely looping action that consumes
  76     // whole statements.
  77     var cc = [statements];
  78     // Context contains information about the current local scope, the
  79     // variables defined in that, and the scopes above it.
  80     var context = null;
  81     // The lexical scope, used mostly for indentation.
  82     var lexical = new TSLexical(-2, 0, "block", false);
  83     // Current column, and the indentation at the start of the current
  84     // line. Used to create lexical scope objects.
  85     var column = 0;
  86     var indented = 0;
  87     // Variables which are used by the mark, cont, and pass functions
  88     // below to communicate with the driver loop in the 'next'
  89     // function.
  90     var consume, marked;
  91
  92     // The iterator object.
  93     var parser = {next: next, copy: copy};
  94
  95     function next(){
  96       // Start by performing any 'lexical' actions (adjusting the
  97       // lexical variable), or the operations below will be working
  98       // with the wrong lexical state.
  99       while(cc[cc.length - 1].lex)
 100         cc.pop()();
 101
 102       // Fetch a token.
 103       var token = tokens.next();
 104       // Adjust column and indented.
 105       if (token.type == "whitespace" && column == 0)
 106         indented = token.value.length;
 107       column += token.value.length;
 108       if (token.type == "newline"){
 109         indented = column = 0;
 110         // If the lexical scope's align property is still undefined at
 111         // the end of the line, it is an un-aligned scope.
 112         if (!("align" in lexical))
 113           lexical.align = false;
 114         // Newline tokens get a lexical context associated with them,
 115         // which is used for indentation.
 116         token.lexicalContext = lexical;
 117       }
 118       // No more processing for meaningless tokens.
 119       if (token.type == "whitespace" || token.type == "newline" || token.type == "comment")
 120         return token;
 121       // When a meaningful token is found and the lexical scope's
 122       // align is undefined, it is an aligned scope.
 123       if (!("align" in lexical))
 124         lexical.align = true;
 125
 126       // Execute actions until one 'consumes' the token and we can
 127       // return it. Marked is used to
 128       while(true){
 129         consume = marked = false;
 130         // Take and execute the topmost action.
 131         cc.pop()(token.type, token.name);
 132         if (consume){
 133           // Marked is used to change the style of the current token.
 134           if (marked)
 135             token.style = marked;
 136
 137           return token;
 138         }
 139       }
 140     }
 141
 142     // This makes a copy of the parser state. It stores all the
 143     // stateful variables in a closure, and returns a function that
 144     // will restore them when called with a new input stream. Note
 145     // that the cc array has to be copied, because it is contantly
 146     // being modified. Lexical objects are not mutated, and context
 147     // objects are not mutated in a harmful way, so they can be shared
 148     // between runs of the parser.
 149     function copy(){
 150       var _context = context, _lexical = lexical, _cc = cc.concat([]), _regexp = tokens.regexp, _comment = tokens.inComment;
 151
 152       return function(input){
 153         context = _context;
 154         lexical = _lexical;
 155         cc = _cc.concat([]); // copies the array
 156         column = indented = 0;
 157         tokens = tokenizeTypoScript(input);
 158         tokens.regexp = _regexp;
 159         tokens.inComment = _comment;
 160         return parser;
 161       };
 162     }
 163
 164     // Helper function for pushing a number of actions onto the cc
 165     // stack in reverse order.
 166     function push(fs){
 167       for (var i = fs.length - 1; i >= 0; i--)
 168         cc.push(fs[i]);
 169     }
 170     // cont and pass are used by the action functions to add other
 171     // actions to the stack. cont will cause the current token to be
 172     // consumed, pass will leave it for the next action.
 173     function cont(){
 174       push(arguments);
 175       consume = true;
 176     }
 177     function pass(){
 178       push(arguments);
 179       consume = false;
 180     }
 181     // Used to change the style of the current token.
 182     function mark(style){
 183       marked = style;
 184     }
 185
 186     // Push a new scope. Will automatically link the the current
 187     // scope.
 188     function pushcontext(){
 189       context = {prev: context, vars: {"this": true, "arguments": true}};
 190     }
 191     // Pop off the current scope.
 192     function popcontext(){
 193       context = context.prev;
 194     }
 195     // Register a variable in the current scope.
 196     function register(varname){
 197       if (context){
 198         mark("variabledef");
 199         context.vars[varname] = true;
 200       }
 201     }
 202
 203
 204     // Push a new lexical context of the given type.
 205     function pushlex(type){
 206       var result = function(){
 207         lexical = new TSLexical(indented, column, type, null, lexical)
 208       };
 209       result.lex = true;
 210       return result;
 211     }
 212     // Pop off the current lexical context.
 213     function poplex(){
 214       lexical = lexical.prev;
 215     }
 216     poplex.lex = true;
 217     // The 'lex' flag on these actions is used by the 'next' function
 218     // to know they can (and have to) be ran before moving on to the
 219     // next token.
 220
 221     // Creates an action that discards tokens until it finds one of
 222     // the given type.
 223     function expect(wanted){
 224       return function(type){
 225         if (type == wanted) cont();
 226         else cont(arguments.callee);
 227       };
 228     }
 229
 230     // Looks for a statement, and then calls itself.
 231     function statements(type){
 232       return pass(statement, statements);
 233     }
 234     // Dispatches various types of statements based on the type of the
 235     // current token.
 236     function statement(type){
 237           if (type == "{")              cont(pushlex("{"), block, poplex);
 238           // else if (type == "[")              cont(pushlex("]"), condition, poplex);
 239       else cont();
 240     }
 241
 242     // Dispatch expression types.
 243     function expression(type){
 244       if (atomicTypes.hasOwnProperty(type)) cont(maybeoperator);
 245       else if (type == "function")                      cont(functiondef);
 246       else if (type == "keyword c")             cont(expression);
 247       else if (type == "(")                             cont(pushlex(")"), expression, expect(")"), poplex);
 248       else if (type == "operator")                      cont(expression);
 249       else if (type == "[")                             cont(pushlex("]"), commasep(expression), expect("]"), poplex);
 250       else if (type == "{")                             cont(pushlex("}"), commasep(objprop), expect("}"), poplex);
 251     }
 252     // Called for places where operators, function calls, or
 253     // subscripts are valid. Will skip on to the next action if none
 254     // is found.
 255     function maybeoperator(type){
 256       if (type == "operator") cont(expression);
 257       else if (type == "(") cont(pushlex(")"), expression, commasep(expression), expect(")"), poplex);
 258       else if (type == ".") cont(property, maybeoperator);
 259       else if (type == "[") cont(pushlex("]"), expression, expect("]"), poplex);
 260     }
 261     // When a statement starts with a variable name, it might be a
 262     // label. If no colon follows, it's a regular statement.
 263     function maybelabel(type){
 264       if (type == ":") cont(poplex, statement);
 265       else pass(maybeoperator, expect(";"), poplex);
 266     }
 267     // Property names need to have their style adjusted -- the
 268     // tokenizer think they are variables.
 269     function property(type){
 270       if (type == "variable") {mark("property"); cont();}
 271     }
 272     // This parses a property and its value in an object literal.
 273     function objprop(type){
 274       if (type == "variable") mark("property");
 275       if (atomicTypes.hasOwnProperty(type)) cont(expect(":"), expression);
 276     }
 277     // Parses a comma-separated list of the things that are recognized
 278     // by the 'what' argument.
 279     function commasep(what){
 280       function proceed(type) {
 281         if (type == ",") cont(what, proceed);
 282       };
 283       return function() {
 284         pass(what, proceed);
 285       };
 286     }
 287
 288     // Look for statements until a closing brace is found.
 289     function block(type){
 290           if (type == "}") cont();
 291       else pass(statement, block);
 292     }
 293
 294     // Look for statements until a closing brace is found.
 295     function condition(type){
 296       if (type == "]") cont();
 297       else pass(statement, block);
 298     }
 299
 300
 301     // Variable definitions are split into two actions -- 1 looks for
 302     // a name or the end of the definition, 2 looks for an '=' sign or
 303     // a comma.
 304     function vardef1(type, value){
 305       if (type == "variable"){register(value); cont(vardef2);}
 306       else cont();
 307     }
 308     function vardef2(type){
 309       if (type == "operator") cont(expression, vardef2);
 310       else if (type == ",") cont(vardef1);
 311     }
 312     // For loops.
 313     function forspec1(type, value){
 314       if (type == "var") cont(vardef1, forspec2);
 315       else cont(expression, forspec2);
 316     }
 317     function forspec2(type){
 318       if (type == ",") cont(forspec1);
 319       if (type == ";") cont(expression, expect(";"), expression);
 320     }
 321     // A function definition creates a new context, and the variables
 322     // in its argument list have to be added to this context.
 323     function functiondef(type, value){
 324       if (type == "variable"){register(value); cont(functiondef);}
 325       else if (type == "(") cont(pushcontext, commasep(funarg), expect(")"), statement, popcontext);
 326     }
 327     function funarg(type, value){
 328       if (type == "variable"){register(value); cont();}
 329     }
 330
 331     return parser;
 332   }
 333 }();