Bug 1823326 - Part 9: Wrap JSStringBuilder to support syntax parser. …

…r=bthrall

Syntax parser does not need string allocation.

Differential Revision: https://phabricator.services.mozilla.com/D174567

js/src/vm/JSONParser.cpp

@@ -99,9 +99,9 @@ JSONToken JSONTokenizer<CharT, ParserT, StringBuilderT>::readString() {
    * of unescaped characters into a temporary buffer, then an escaped
    * character, and repeat until the entire string is consumed.
    */
-  JSStringBuilder buffer(parser->handler.cx);
+  StringBuilderT builder(parser->handler.cx);
   do {
-    if (start < current && !buffer.append(start.get(), current.get())) {
+    if (start < current && !builder.append(start.get(), current.get())) {
       return token(JSONToken::OOM);
     }
 
@@ -111,7 +111,7 @@ JSONToken JSONTokenizer<CharT, ParserT, StringBuilderT>::readString() {
 
     char16_t c = *current++;
     if (c == '"') {
-      return stringToken<ST>(buffer);
+      return stringToken<ST>(builder);
     }
 
     if (c != '\\') {
@@ -183,7 +183,7 @@ JSONToken JSONTokenizer<CharT, ParserT, StringBuilderT>::readString() {
         error("bad escaped character");
         return token(JSONToken::Error);
     }
-    if (!buffer.append(c)) {
+    if (!builder.append(c)) {
       return token(JSONToken::OOM);
     }
 
@@ -617,10 +617,10 @@ inline bool JSONFullParseHandler<CharT>::setStringValue(CharPtr start,
 template <typename CharT>
 template <JSONStringType ST>
 inline bool JSONFullParseHandler<CharT>::setStringValue(
-    JSStringBuilder& builder) {
+    StringBuilder& builder) {
   JSLinearString* str = (ST == JSONStringType::PropertyName)
-                            ? builder.finishAtom()
-                            : builder.finishString();
+                            ? builder.buffer.finishAtom()
+                            : builder.buffer.finishString();
   if (!str) {
     return false;
   }
@@ -773,6 +773,17 @@ void JSONParser<CharT>::error(const char* msg) {
   handler.reportError(msg, lineNumber, columnNumber);
 }
 
+template <typename CharT>
+bool JSONFullParseHandler<CharT>::StringBuilder::append(char16_t c) {
+  return buffer.append(c);
+}
+
+template <typename CharT>
+bool JSONFullParseHandler<CharT>::StringBuilder::append(const CharT* begin,
+                                                        const CharT* end) {
+  return buffer.append(begin, end);
+}
+
 template <typename CharT>
 JSONParser<CharT>::~JSONParser() {
   for (size_t i = 0; i < stack.length(); i++) {

js/src/vm/JSONParser.h

@@ -13,12 +13,11 @@
 #include "jspubtd.h"
 
 #include "ds/IdValuePair.h"
+#include "util/StringBuffer.h"
 #include "vm/StringType.h"
 
 namespace js {
 
-class JSStringBuilder;
-
 enum class JSONToken {
   String,
   Number,
@@ -268,6 +267,16 @@ class MOZ_STACK_CLASS JSONFullParseHandler
   using CharPtr = mozilla::RangedPtr<const CharT>;
 
  public:
+  class StringBuilder {
+   public:
+    JSStringBuilder buffer;
+
+    explicit StringBuilder(JSContext* cx) : buffer(cx) {}
+
+    bool append(char16_t c);
+    bool append(const CharT* begin, const CharT* end);
+  };
+
   JSONFullParseHandler(JSContext* cx, ParseType parseType)
       : Base(cx, parseType) {}
 
@@ -280,17 +289,22 @@ class MOZ_STACK_CLASS JSONFullParseHandler
   template <JSONStringType ST>
   inline bool setStringValue(CharPtr start, size_t length);
   template <JSONStringType ST>
-  inline bool setStringValue(JSStringBuilder& builder);
+  inline bool setStringValue(StringBuilder& builder);
 
   void reportError(const char* msg, const char* lineString,
                    const char* columnString);
 };
 
 template <typename CharT>
 class MOZ_STACK_CLASS JSONParser {
-  using Tokenizer = JSONTokenizer<CharT, JSONParser<CharT>, JSStringBuilder>;
   using Handler = JSONFullParseHandler<CharT>;
 
+ public:
+  using StringBuilder = typename Handler::StringBuilder;
+
+ private:
+  using Tokenizer = JSONTokenizer<CharT, JSONParser<CharT>, StringBuilder>;
+
  public:
   Handler handler;
   Tokenizer tokenizer;