move columns calculation via buffer back

csstree · Jan 15, 2017 · 58175e6 · 58175e6
1 parent eea5e94
commit 58175e6
Showing 1 changed file with 19 additions and 33 deletions.
diff --git a/lib/scanner/index.js b/lib/scanner/index.js
@@ -40,36 +40,43 @@ var MIN_BUFFER_SIZE = 16 * 1024;
 var OFFSET_MASK = 0x00FFFFFF;
 var TYPE_OFFSET = 24;
 var SafeUint32Array = typeof Uint32Array !== 'undefined' ? Uint32Array : Array; // fallback on Array when TypedArray is not supported
-var lastIndexOf = Array.prototype.lastIndexOf; // some browser implementations have no TypedArray#lastIndexOf
 
-function computeLines(scanner, source) {
+function computeLinesAndColumns(scanner, source) {
     var sourceLength = source.length;
     var start = firstCharOffset(source);
     var lines = scanner.lines;
     var line = scanner.initLine;
+    var columns = scanner.columns;
+    var column = scanner.initColumn;
 
     if (lines === null || lines.length < sourceLength + 1) {
         lines = new SafeUint32Array(Math.max(sourceLength + 1024, MIN_BUFFER_SIZE));
+        columns = new SafeUint32Array(lines.length);
     }
 
     for (var i = start; i < sourceLength; i++) {
         var code = source.charCodeAt(i);
 
         lines[i] = line;
+        columns[i] = column++;
 
         if (code === N || code === R || code === F) {
             if (code === R && i + 1 < sourceLength && source.charCodeAt(i + 1) === N) {
                 i++;
                 lines[i] = line;
+                columns[i] = column;
             }
+
             line++;
+            column = 1;
         }
     }
 
     lines[i] = line;
 
-    scanner.lineComputed = true;
+    scanner.linesAnsColumnsComputed = true;
     scanner.lines = lines;
+    scanner.columns = columns;
 }
 
 function tokenLayout(scanner, source, startPos) {
@@ -148,6 +155,7 @@ function tokenLayout(scanner, source, startPos) {
 var Scanner = function(source, initLine, initColumn) {
     this.offsetAndType = null;
     this.lines = null;
+    this.columns = null;
 
     this.setSource(source || '', initLine, initColumn);
 };
@@ -158,10 +166,8 @@ Scanner.prototype = {
 
         this.source = source;
         this.initLine = typeof initLine === 'undefined' ? 1 : initLine;
-        this.initColumn = (typeof initColumn === 'undefined' ? 1 : initColumn) - start;
-        this.lastLocationLine = this.initLine;
-        this.lastLocationLineOffset = 1 - this.initColumn;
-        this.lineComputed = false;
+        this.initColumn = typeof initColumn === 'undefined' ? 1 : initColumn;
+        this.linesAnsColumnsComputed = false;
 
         this.eof = false;
         this.currentToken = -1;
@@ -250,36 +256,16 @@ Scanner.prototype = {
         this.next();
     },
 
-    getLocation: function(offset, source) {
-        if (!this.lineComputed) {
-            computeLines(this, this.source);
-        }
-
-        var line = this.lines[offset];
-        var column = offset;
-        var lineOffset;
-
-        if (line === this.initLine) {
-            column += this.initColumn;
-        } else {
-            // try get precomputed line offset
-            if (line === this.lastLocationLine) {
-                lineOffset = this.lastLocationLineOffset;
-            } else {
-                // try avoid to compute line offset since it's expensive for long lines
-                lineOffset = lastIndexOf.call(this.lines, line - 1, offset);
-                this.lastLocationLine = line;
-                this.lastLocationLineOffset = lineOffset;
-            }
-
-            column -= lineOffset;
+    getLocation: function(offset, filename) {
+        if (!this.linesAnsColumnsComputed) {
+            computeLinesAndColumns(this, this.source);
         }
 
         return {
-            source: source,
+            source: filename,
             offset: offset,
-            line: line,
-            column: column
+            line: this.lines[offset],
+            column: this.columns[offset]
         };
     },