Implement ES6 Template Literals

src/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/ast.h"
 #include "src/bailout-reason.h"
 #include "src/base/platform/platform.h"
@@ skipping 795 matching lines @@
       pre_parse_timer_(NULL) {
   DCHECK(!script().is_null() || info->source_stream() != NULL);
   set_allow_harmony_scoping(!info->is_native() && FLAG_harmony_scoping);
   set_allow_modules(!info->is_native() && FLAG_harmony_modules);
   set_allow_natives_syntax(FLAG_allow_natives_syntax || info->is_native());
   set_allow_lazy(false);  // Must be explicitly enabled.
   set_allow_arrow_functions(FLAG_harmony_arrow_functions);
   set_allow_harmony_numeric_literals(FLAG_harmony_numeric_literals);
   set_allow_classes(FLAG_harmony_classes);
   set_allow_harmony_object_literals(FLAG_harmony_object_literals);
+  set_allow_harmony_templates(FLAG_harmony_templates);
   for (int feature = 0; feature < v8::Isolate::kUseCounterFeatureCount;
        ++feature) {
     use_counts_[feature] = 0;
   }
   if (info->ast_value_factory() == NULL) {
     // info takes ownership of AstValueFactory.
     info->SetAstValueFactory(
         new AstValueFactory(zone(), parse_info->hash_seed));
   }
 }
@@ skipping 3074 matching lines @@
     reusable_preparser_->set_allow_harmony_scoping(allow_harmony_scoping());
     reusable_preparser_->set_allow_modules(allow_modules());
     reusable_preparser_->set_allow_natives_syntax(allow_natives_syntax());
     reusable_preparser_->set_allow_lazy(true);
     reusable_preparser_->set_allow_arrow_functions(allow_arrow_functions());
     reusable_preparser_->set_allow_harmony_numeric_literals(
         allow_harmony_numeric_literals());
     reusable_preparser_->set_allow_classes(allow_classes());
     reusable_preparser_->set_allow_harmony_object_literals(
         allow_harmony_object_literals());
+    reusable_preparser_->set_allow_harmony_templates(allow_harmony_templates());
   }
   PreParser::PreParseResult result =
       reusable_preparser_->PreParseLazyFunction(strict_mode(),
                                                 is_generator(),
                                                 logger);
   if (pre_parse_timer_ != NULL) {
     pre_parse_timer_->Stop();
   }
   return result;
 }
@@ skipping 1098 matching lines @@
   info()->SetFunction(result);
 
   // We cannot internalize on a background thread; a foreground task will take
   // care of calling Parser::Internalize just before compilation.
 
   if (compile_options() == ScriptCompiler::kProduceParserCache) {
     if (result != NULL) *info_->cached_data() = recorder.GetScriptData();
     log_ = NULL;
   }
 }
+
+
+ParserTraits::TemplateLiteralState Parser::OpenTemplateLiteral(int pos) {
+  return new (zone()) ParserTraits::TemplateLiteral(zone(), pos);
+}
+
+
+void Parser::AddTemplateSpan(TemplateLiteralState* state, bool tail) {
+  int pos = scanner()->location().beg_pos;
+  int end = scanner()->location().end_pos - (tail ? 1 : 2);
+  const AstRawString* tv = scanner()->CurrentSymbol(ast_value_factory());
+  Literal* cooked = factory()->NewStringLiteral(tv, pos);
+  (*state)->AddTemplateSpan(cooked, end, zone());
+}
+
+
+void Parser::AddTemplateExpression(TemplateLiteralState* state,
+                                   Expression* expression) {
+  (*state)->AddExpression(expression, zone());
+}
+
+
+Expression* Parser::CloseTemplateLiteral(TemplateLiteralState* state,
+                                         int start, Expression* tag) {
+#define COOKED_STRING(i) cooked_strings->at(i)

[rossberg, 2014/11/14 12:28:07]

Nit: please remove these macros, they don't seem worth it.

+#define POS(i) cooked_strings->at(i)->position()
+#define EXPR(i) expressions->at(i)
+  TemplateLiteral* lit = *state;
+  int pos = lit->position();
+  const ZoneList<Expression*>* cooked_strings = lit->cooked();
+  const ZoneList<Expression*>* expressions = lit->expressions();
+  CHECK(cooked_strings->length() == (expressions->length() + 1));
+
+  if (!tag) {
+    // Build tree of BinaryOps to simplify code-generation
+    Expression* expr = NULL;
+
+    if (expressions->length() == 0) {
+      // Simple case: treat as string literal
+      expr = COOKED_STRING(0);
+    } else {
+      int i;
+      expr = factory()->NewBinaryOperation(Token::ADD,
+          COOKED_STRING(0), EXPR(0), POS(0));
+      for (i = 1; i < expressions->length(); ++i) {
+        expr = factory()->NewBinaryOperation(Token::ADD,
+            expr, factory()->NewBinaryOperation(Token::ADD, COOKED_STRING(i),
+            EXPR(i), POS(i)), POS(i));

[rossberg, 2014/11/14 12:28:07]

Nit: indentation?

+      }
+      expr = factory()->NewBinaryOperation(Token::ADD, expr, COOKED_STRING(i),
+          POS(i));
+    }
+    return expr;
+  } else {
+    ZoneList<Expression*>* raw_strings = TemplateRawStrings(lit);
+    Handle<String> source(String::cast(script()->source()));
+
+    int cooked_idx = function_state_->NextMaterializedLiteralIndex();
+    int raw_idx = function_state_->NextMaterializedLiteralIndex();
+
+    // GetTemplateCallSite
+    ZoneList<Expression*>* args = new (zone()) ZoneList<Expression*>(4, zone());
+    args->Add(factory()->NewArrayLiteral(
+        const_cast<ZoneList<Expression*>*>(cooked_strings), cooked_idx, pos),
+        zone());
+    args->Add(factory()->NewArrayLiteral(
+        const_cast<ZoneList<Expression*>*>(raw_strings), raw_idx, pos), zone());
+    this->CheckPossibleEvalCall(tag, scope_);
+    Expression* expr = factory()->NewCallRuntime(

[rossberg, 2014/11/14 12:28:07]

Nit: rename from 'expr' to 'call_site'

+        ast_value_factory()->get_template_callsite_string(), NULL, args, start);
+
+    // Call TagFn
+    ZoneList<Expression*>* call_args = new (zone()) ZoneList<Expression*>(
+        expressions->length() + 1, zone());
+    call_args->Add(expr, zone());
+    call_args->AddAll(*expressions, zone());
+    expr = factory()->NewCall(tag, call_args, pos);
+    return expr;
+  }
+#undef COOKED_STRING
+#undef POS
+#undef EXPR
+}
+
+
+ZoneList<Expression*>* Parser::TemplateRawStrings(const TemplateLiteral* lit) {
+  const ZoneList<int>* lengths = lit->lengths();
+  const ZoneList<Expression*>* cooked_strings = lit->cooked();
+  int total = lengths->length();
+  ZoneList<Expression*>* raw_strings;
+  SmartArrayPointer<char> raw_chars;
+
+  // Given a TemplateLiteral, produce a list of raw strings, used for generating
+  // a CallSite object for a tagged template invocations.
+  //
+  // A raw string will consist of the unescaped characters of a template span,
+  // with end-of-line sequences normalized to U+000A LINE FEEDs, and without
+  // leading or trailing template delimiters.
+  //
+
+  DCHECK(total);
+
+  Handle<String> source(String::cast(script()->source()));
+
+  raw_strings = new (zone()) ZoneList<Expression*>(total, zone());
+
+  for (int index = 0; index < total; ++index) {
+    int span_start = cooked_strings->at(index)->position() + 1;
+    int span_end = lengths->at(index) - 1;
+    int length;
+    int to_index = 0;
+
+    raw_chars = source->ToCString(
+        ALLOW_NULLS, FAST_STRING_TRAVERSAL, span_start, span_end, &length);
+
+    // Normalize raw line-feeds. [U+000D U+000A] (CRLF) and [U+000D] (CR) must
+    // be translated into U+000A (LF).
+    for (int from_index = 0; from_index < length; ++from_index) {
+      char ch = raw_chars[from_index];
+      if (ch == '\r') {
+        if (raw_chars[from_index + 1] == '\n') {

[rossberg, 2014/11/14 12:28:07]

Perhaps add a comment explaining that it is actually safe to access index+1 here
without checking against the length first.

[caitp (gmail), 2014/11/14 13:25:18]

Hmm, I'm not sure this is guaranteed to be safe, actually. Adding a check.

+          ++from_index;
+        }
+        ch = '\n';

[rossberg, 2014/11/14 12:28:07]

Nit: put this first.

+      }
+      raw_chars[to_index++] = ch;
+    }
+
+    const AstRawString* raw_str = ast_value_factory()->GetOneByteString(
+        OneByteVector(raw_chars.get(), to_index));
+    Literal* raw_lit = factory()->NewStringLiteral(raw_str, span_start - 1);
+    raw_strings->Add(raw_lit, zone());
+  }
+
+  return raw_strings;
+}
+
 } }  // namespace v8::internal