353 lines
13 KiB
JavaScript
353 lines
13 KiB
JavaScript
/* Parse function for JavaScript. Makes use of the tokenizer from
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* tokenizejavascript.js. Note that your parsers do not have to be
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* this complicated -- if you don't want to recognize local variables,
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* in many languages it is enough to just look for braces, semicolons,
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* parentheses, etc, and know when you are inside a string or comment.
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*
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* See manual.html for more info about the parser interface.
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*/
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var JSParser = Editor.Parser = (function() {
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// Token types that can be considered to be atoms.
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var atomicTypes = {"atom": true, "number": true, "variable": true, "string": true, "regexp": true};
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// Setting that can be used to have JSON data indent properly.
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var json = false;
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// Constructor for the lexical context objects.
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function JSLexical(indented, column, type, align, prev, info) {
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// indentation at start of this line
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this.indented = indented;
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// column at which this scope was opened
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this.column = column;
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// type of scope ('vardef', 'stat' (statement), 'form' (special form), '[', '{', or '(')
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this.type = type;
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// '[', '{', or '(' blocks that have any text after their opening
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// character are said to be 'aligned' -- any lines below are
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// indented all the way to the opening character.
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if (align != null)
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this.align = align;
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// Parent scope, if any.
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this.prev = prev;
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this.info = info;
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}
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// My favourite JavaScript indentation rules.
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function indentJS(lexical) {
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return function(firstChars) {
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var firstChar = firstChars && firstChars.charAt(0), type = lexical.type;
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var closing = firstChar == type;
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if (type == "vardef")
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return lexical.indented + 4;
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else if (type == "form" && firstChar == "{")
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return lexical.indented;
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else if (type == "stat" || type == "form")
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return lexical.indented + indentUnit;
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else if (lexical.info == "switch" && !closing)
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return lexical.indented + (/^(?:case|default)\b/.test(firstChars) ? indentUnit : 2 * indentUnit);
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else if (lexical.align)
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return lexical.column - (closing ? 1 : 0);
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else
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return lexical.indented + (closing ? 0 : indentUnit);
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};
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}
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// The parser-iterator-producing function itself.
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function parseJS(input, basecolumn) {
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// Wrap the input in a token stream
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var tokens = tokenizeJavaScript(input);
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// The parser state. cc is a stack of actions that have to be
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// performed to finish the current statement. For example we might
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// know that we still need to find a closing parenthesis and a
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// semicolon. Actions at the end of the stack go first. It is
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// initialized with an infinitely looping action that consumes
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// whole statements.
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var cc = [json ? singleExpr : statements];
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// Context contains information about the current local scope, the
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// variables defined in that, and the scopes above it.
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var context = null;
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// The lexical scope, used mostly for indentation.
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var lexical = new JSLexical((basecolumn || 0) - indentUnit, 0, "block", false);
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// Current column, and the indentation at the start of the current
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// line. Used to create lexical scope objects.
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var column = 0;
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var indented = 0;
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// Variables which are used by the mark, cont, and pass functions
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// below to communicate with the driver loop in the 'next'
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// function.
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var consume, marked;
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// The iterator object.
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var parser = {next: next, copy: copy};
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function next(){
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// Start by performing any 'lexical' actions (adjusting the
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// lexical variable), or the operations below will be working
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// with the wrong lexical state.
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while(cc[cc.length - 1].lex)
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cc.pop()();
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// Fetch a token.
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var token = tokens.next();
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// Adjust column and indented.
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if (token.type == "whitespace" && column == 0)
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indented = token.value.length;
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column += token.value.length;
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if (token.content == "\n"){
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indented = column = 0;
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// If the lexical scope's align property is still undefined at
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// the end of the line, it is an un-aligned scope.
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if (!("align" in lexical))
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lexical.align = false;
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// Newline tokens get an indentation function associated with
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// them.
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token.indentation = indentJS(lexical);
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}
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// No more processing for meaningless tokens.
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if (token.type == "whitespace" || token.type == "comment")
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return token;
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// When a meaningful token is found and the lexical scope's
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// align is undefined, it is an aligned scope.
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if (!("align" in lexical))
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lexical.align = true;
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// Execute actions until one 'consumes' the token and we can
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// return it.
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while(true) {
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consume = marked = false;
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// Take and execute the topmost action.
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cc.pop()(token.type, token.content);
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if (consume){
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// Marked is used to change the style of the current token.
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if (marked)
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token.style = marked;
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// Here we differentiate between local and global variables.
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else if (token.type == "variable" && inScope(token.content))
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token.style = "js-localvariable";
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return token;
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}
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}
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}
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// This makes a copy of the parser state. It stores all the
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// stateful variables in a closure, and returns a function that
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// will restore them when called with a new input stream. Note
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// that the cc array has to be copied, because it is contantly
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// being modified. Lexical objects are not mutated, and context
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// objects are not mutated in a harmful way, so they can be shared
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// between runs of the parser.
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function copy(){
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var _context = context, _lexical = lexical, _cc = cc.concat([]), _tokenState = tokens.state;
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return function copyParser(input){
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context = _context;
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lexical = _lexical;
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cc = _cc.concat([]); // copies the array
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column = indented = 0;
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tokens = tokenizeJavaScript(input, _tokenState);
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return parser;
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};
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}
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// Helper function for pushing a number of actions onto the cc
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// stack in reverse order.
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function push(fs){
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for (var i = fs.length - 1; i >= 0; i--)
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cc.push(fs[i]);
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}
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// cont and pass are used by the action functions to add other
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// actions to the stack. cont will cause the current token to be
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// consumed, pass will leave it for the next action.
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function cont(){
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push(arguments);
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consume = true;
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}
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function pass(){
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push(arguments);
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consume = false;
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}
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// Used to change the style of the current token.
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function mark(style){
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marked = style;
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}
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// Push a new scope. Will automatically link the current scope.
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function pushcontext(){
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context = {prev: context, vars: {"this": true, "arguments": true}};
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}
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// Pop off the current scope.
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function popcontext(){
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context = context.prev;
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}
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// Register a variable in the current scope.
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function register(varname){
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if (context){
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mark("js-variabledef");
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context.vars[varname] = true;
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}
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}
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// Check whether a variable is defined in the current scope.
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function inScope(varname){
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var cursor = context;
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while (cursor) {
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if (cursor.vars[varname])
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return true;
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cursor = cursor.prev;
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}
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return false;
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}
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// Push a new lexical context of the given type.
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function pushlex(type, info) {
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var result = function(){
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lexical = new JSLexical(indented, column, type, null, lexical, info)
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};
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result.lex = true;
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return result;
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}
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// Pop off the current lexical context.
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function poplex(){
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lexical = lexical.prev;
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}
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poplex.lex = true;
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// The 'lex' flag on these actions is used by the 'next' function
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// to know they can (and have to) be ran before moving on to the
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// next token.
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// Creates an action that discards tokens until it finds one of
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// the given type.
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function expect(wanted){
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return function expecting(type){
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if (type == wanted) cont();
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else cont(arguments.callee);
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};
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}
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// Looks for a statement, and then calls itself.
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function statements(type){
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return pass(statement, statements);
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}
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function singleExpr(type){
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return pass(expression, statements);
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}
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// Dispatches various types of statements based on the type of the
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// current token.
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function statement(type){
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if (type == "var") cont(pushlex("vardef"), vardef1, expect(";"), poplex);
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else if (type == "keyword a") cont(pushlex("form"), expression, statement, poplex);
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else if (type == "keyword b") cont(pushlex("form"), statement, poplex);
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else if (type == "{") cont(pushlex("}"), block, poplex);
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else if (type == "function") cont(functiondef);
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else if (type == "for") cont(pushlex("form"), expect("("), pushlex(")"), forspec1, expect(")"), poplex, statement, poplex);
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else if (type == "variable") cont(pushlex("stat"), maybelabel);
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else if (type == "switch") cont(pushlex("form"), expression, pushlex("}", "switch"), expect("{"), block, poplex, poplex);
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else if (type == "case") cont(expression, expect(":"));
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else if (type == "default") cont(expect(":"));
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else if (type == "catch") cont(pushlex("form"), pushcontext, expect("("), funarg, expect(")"), statement, poplex, popcontext);
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else pass(pushlex("stat"), expression, expect(";"), poplex);
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}
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// Dispatch expression types.
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function expression(type){
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if (atomicTypes.hasOwnProperty(type)) cont(maybeoperator);
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else if (type == "function") cont(functiondef);
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else if (type == "keyword c") cont(expression);
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else if (type == "(") cont(pushlex(")"), expression, expect(")"), poplex, maybeoperator);
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else if (type == "operator") cont(expression);
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else if (type == "[") cont(pushlex("]"), commasep(expression, "]"), poplex, maybeoperator);
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else if (type == "{") cont(pushlex("}"), commasep(objprop, "}"), poplex, maybeoperator);
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}
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// Called for places where operators, function calls, or
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// subscripts are valid. Will skip on to the next action if none
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// is found.
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function maybeoperator(type){
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if (type == "operator") cont(expression);
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else if (type == "(") cont(pushlex(")"), expression, commasep(expression, ")"), poplex, maybeoperator);
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else if (type == ".") cont(property, maybeoperator);
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else if (type == "[") cont(pushlex("]"), expression, expect("]"), poplex, maybeoperator);
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}
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// When a statement starts with a variable name, it might be a
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// label. If no colon follows, it's a regular statement.
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function maybelabel(type){
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if (type == ":") cont(poplex, statement);
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else pass(maybeoperator, expect(";"), poplex);
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}
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// Property names need to have their style adjusted -- the
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// tokenizer thinks they are variables.
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function property(type){
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if (type == "variable") {mark("js-property"); cont();}
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}
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// This parses a property and its value in an object literal.
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function objprop(type){
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if (type == "variable") mark("js-property");
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if (atomicTypes.hasOwnProperty(type)) cont(expect(":"), expression);
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}
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// Parses a comma-separated list of the things that are recognized
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// by the 'what' argument.
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function commasep(what, end){
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function proceed(type) {
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if (type == ",") cont(what, proceed);
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else if (type == end) cont();
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else cont(expect(end));
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}
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return function commaSeparated(type) {
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if (type == end) cont();
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else pass(what, proceed);
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};
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}
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// Look for statements until a closing brace is found.
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function block(type){
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if (type == "}") cont();
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else pass(statement, block);
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}
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// Variable definitions are split into two actions -- 1 looks for
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// a name or the end of the definition, 2 looks for an '=' sign or
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// a comma.
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function vardef1(type, value){
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if (type == "variable"){register(value); cont(vardef2);}
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else cont();
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}
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function vardef2(type, value){
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if (value == "=") cont(expression, vardef2);
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else if (type == ",") cont(vardef1);
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}
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// For loops.
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function forspec1(type){
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if (type == "var") cont(vardef1, forspec2);
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else if (type == ";") pass(forspec2);
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else if (type == "variable") cont(formaybein);
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else pass(forspec2);
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}
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function formaybein(type, value){
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if (value == "in") cont(expression);
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else cont(maybeoperator, forspec2);
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}
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function forspec2(type, value){
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if (type == ";") cont(forspec3);
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else if (value == "in") cont(expression);
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else cont(expression, expect(";"), forspec3);
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}
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function forspec3(type) {
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if (type == ")") pass();
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else cont(expression);
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}
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// A function definition creates a new context, and the variables
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// in its argument list have to be added to this context.
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function functiondef(type, value){
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if (type == "variable"){register(value); cont(functiondef);}
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else if (type == "(") cont(pushcontext, commasep(funarg, ")"), statement, popcontext);
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}
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function funarg(type, value){
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if (type == "variable"){register(value); cont();}
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}
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return parser;
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}
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return {
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make: parseJS,
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electricChars: "{}:",
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configure: function(obj) {
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if (obj.json != null) json = obj.json;
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}
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};
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})();
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