Avoid re-lexing, move position to internal state

Instead of passing around the current position as an argument, we now have a
parser property called pos to keep track of that.  Instead of repeatedly
re-lexing at the current position we now have a property called nextToken
which contains the token beginning at the current position.  We may need to
re-lex if we switch mode.  Since the position is kept in the parser state,
we don't need to return it from parsing methods, which obsoletes the
ParseResult class.

src/environments.js

@@ -3,39 +3,37 @@ var parseData = require("./parseData");
 var ParseError = require("./ParseError");
 
 var ParseNode = parseData.ParseNode;
-var ParseResult = parseData.ParseResult;
 
 /**
  * Parse the body of the environment, with rows delimited by \\ and
  * columns delimited by &, and create a nested list in row-major order
  * with one group per cell.
  */
-function parseArray(parser, pos, result) {
+function parseArray(parser, result) {
     var row = [], body = [row], rowGaps = [];
     while (true) {
-        var cell = parser.parseExpression(pos, false, null);
-        row.push(new ParseNode("ordgroup", cell.result, parser.mode));
-        pos = cell.position;
-        var next = cell.peek.text;
+        var cell = parser.parseExpression(false, null);
+        row.push(new ParseNode("ordgroup", cell, parser.mode));
+        var next = parser.nextToken.text;
         if (next === "&") {
-            pos = cell.peek.position;
+            parser.consume();
         } else if (next === "\\end") {
             break;
         } else if (next === "\\\\" || next === "\\cr") {
-            var cr = parser.parseFunction(pos);
-            rowGaps.push(cr.result.value.size);
-            pos = cr.position;
+            var cr = parser.parseFunction();
+            rowGaps.push(cr.value.size);
             row = [];
             body.push(row);
         } else {
+            // TODO: Clean up the following hack once #385 got merged
+            var pos = Math.min(parser.pos + 1, parser.lexer._input.length);
             throw new ParseError("Expected & or \\\\ or \\end",
-                                 parser.lexer, cell.peek.position);
+                                 parser.lexer, pos);
         }
     }
     result.body = body;
     result.rowGaps = rowGaps;
-    return new ParseResult(
-        new ParseNode(result.type, result, parser.mode), pos);
+    return new ParseNode(result.type, result, parser.mode);
 }
 
 /*
@@ -55,7 +53,6 @@ function parseArray(parser, pos, result) {
  *  - context: information and references provided by the parser
  *  - args: an array of arguments passed to \begin{name}
  * The context contains the following properties:
- *  - pos: the current position of the parser.
  *  - envName: the name of the environment, one of the listed names.
  *  - parser: the parser object
  *  - lexer: the lexer object
@@ -90,8 +87,6 @@ defineEnvironment("array", {
     numArgs: 1
 }, function(context, args) {
     var colalign = args[0];
-    var lexer = context.lexer;
-    var positions = context.positions;
     colalign = colalign.value.map ? colalign.value : [colalign];
     var cols = colalign.map(function(node) {
         var ca = node.value;
@@ -108,14 +103,14 @@ defineEnvironment("array", {
         }
         throw new ParseError(
             "Unknown column alignment: " + node.value,
-            lexer, positions[1]);
+            context.lexer, context.positions[1]);
     });
     var res = {
         type: "array",
         cols: cols,
         hskipBeforeAndAfter: true // \@preamble in lttab.dtx
     };
-    res = parseArray(context.parser, context.pos, res);
+    res = parseArray(context.parser, res);
     return res;
 });
 
@@ -142,10 +137,10 @@ defineEnvironment([
         type: "array",
         hskipBeforeAndAfter: false // \hskip -\arraycolsep in amsmath
     };
-    res = parseArray(context.parser, context.pos, res);
+    res = parseArray(context.parser, res);
     if (delimiters) {
-        res.result = new ParseNode("leftright", {
-            body: [res.result],
+        res = new ParseNode("leftright", {
+            body: [res],
             left: delimiters[0],
             right: delimiters[1]
         }, context.mode);
@@ -173,9 +168,9 @@ defineEnvironment("cases", {
             postgap: 0
         }]
     };
-    res = parseArray(context.parser, context.pos, res);
-    res.result = new ParseNode("leftright", {
-        body: [res.result],
+    res = parseArray(context.parser, res);
+    res = new ParseNode("leftright", {
+        body: [res],
         left: "\\{",
         right: "."
     }, context.mode);