tracing: Stream processing for some importers

tracing/tracing/importer/simple_line_reader.html

Index: tracing/tracing/importer/simple_line_reader.html
diff --git a/tracing/tracing/importer/simple_line_reader.html b/tracing/tracing/importer/simple_line_reader.html
index 636c9e88585a58534928378811ad399703399432..2fea194a68c4001f93096f42539123fd194d1798 100644
--- a/tracing/tracing/importer/simple_line_reader.html
+++ b/tracing/tracing/importer/simple_line_reader.html
@@ -9,42 +9,75 @@ found in the LICENSE file.
 'use strict';
 
 tr.exportTo('tr.importer', function() {
-  /**
-   * @constructor
-   */
-  function SimpleLineReader(text) {
-    this.lines_ = text.split('\n');
-    this.curLine_ = 0;
-
-    this.savedLines_ = undefined;
-  }
+  class SimpleLineReader {
+    constructor(text) {
+      this.data_ = text instanceof tr.b.TraceStream ? text : text.split('\n');
+      this.curLine_ = 0;
+      this.readLastLine_ = false;
+      this.savedLines_ = undefined;
+    }
 
-  SimpleLineReader.prototype = {
-    advanceToLineMatching: function(regex) {
-      for (; this.curLine_ < this.lines_.length; this.curLine_++) {
-        var line = this.lines_[this.curLine_];
-        if (this.savedLines_ !== undefined) {
-          this.savedLines_.push(line);
+    * [Symbol.iterator]() {
+      let lastLine = undefined;
+      while (this.hasData_) {
+        if (this.readLastLine_) {
+          this.curLine_++;
+          this.readLastLine_ = false;
+        } else if (this.data_ instanceof tr.b.TraceStream) {
+          this.curLine_++;
+          let line = this.data_.readUntilDelimiter('\n');
+          lastLine = line.endsWith('\n') ? line.slice(0, -1) : line;
+        } else {
+          this.curLine_++;
+          lastLine = this.data_[this.curLine_ - 1];
         }
-        if (regex.test(line)) return true;
+        yield lastLine;
       }
-      return false;
-    },
+    }
 
     get curLineNumber() {
       return this.curLine_;
-    },
+    }
+
+    get hasData_() {
+      if (this.data_ instanceof tr.b.TraceStream) return this.data_.hasData;
+      return this.curLine_ < this.data_.length;
+    }
+
+    advanceToLineMatching(regex) {
+      for (const line of this) {
+        if (this.savedLines_ !== undefined) this.savedLines_.push(line);
+        if (regex.test(line)) {
+          this.goBack_();
+          return true;
+        }
+      }
+      return false;
+    }
+
+    goBack_() {
+      if (this.readLastLine_) {
+        throw new Error('There should be at least one nextLine call between ' +
+                        'any two goBack calls.');
+      }
+      if (this.curLine_ === 0) {
+        throw new Error('There should be at least one nextLine call before ' +
+                        'the first goBack call.');
+      }
+      this.readLastLine_ = true;
+      this.curLine_--;
+    }
 
-    beginSavingLines: function() {
+    beginSavingLines() {
       this.savedLines_ = [];
-    },
+    }
 
-    endSavingLinesAndGetResult: function() {
+    endSavingLinesAndGetResult() {
       var tmp = this.savedLines_;
       this.savedLines_ = undefined;
       return tmp;
     }
-  };
+  }
 
   return {
     SimpleLineReader,