commit 6dbfafe639507c60a00201baa14e293c69315695
author nharmata <nharmata@google.com> Tue Feb 05 08:55:07 2019 -0800
committer Copybara-Service <copybara-piper@google.com> Tue Feb 05 08:57:00 2019 -0800
tree 075c886c7230bab9b606443bee203ae00d4bc7b5
parent d922a1e5faa83d209556694674c6c93c8538c39f

In Parser, dedupe the String instances referred to by StringLiteral instances. Implement the same optimization in the serialization code.

Some .bzl files have tons of duplicate string constants.

We can't dedupe the StringLiteral instances themselves, because they all have different Locations.

RELNOTES: None
PiperOrigin-RevId: 232495067

src/main/java/com/google/devtools/build/lib/syntax/Parser.java

diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
index dea8f33..000c6de 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
@@ -19,7 +19,9 @@
 import com.google.common.base.Supplier;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Interner;
 import com.google.common.collect.Iterables;
+import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
@@ -164,6 +166,8 @@
   private int errorsCount;
   private boolean recoveryMode;  // stop reporting errors until next statement
 
+  private final Interner<String> stringInterner = BlazeInterners.newStrongInterner();
+
   private Parser(Lexer lexer, EventHandler eventHandler) {
     this.lexer = lexer;
     this.eventHandler = eventHandler;
@@ -599,7 +603,8 @@
     Preconditions.checkState(token.kind == TokenKind.STRING);
     int end = token.right;
     StringLiteral literal =
-        setLocation(new StringLiteral((String) token.value), token.left, end);
+        setLocation(
+            new StringLiteral(stringInterner.intern((String) token.value)), token.left, end);
 
     nextToken();
     if (token.kind == TokenKind.STRING) {
@@ -958,7 +963,7 @@
       if (expr instanceof StringLiteral && secondary instanceof StringLiteral) {
         StringLiteral left = (StringLiteral) expr;
         StringLiteral right = (StringLiteral) secondary;
-        return new StringLiteral(left.getValue() + right.getValue());
+        return new StringLiteral(stringInterner.intern(left.getValue() + right.getValue()));
       }
     }
     return new BinaryOperatorExpression(operator, expr, secondary);