Reviewers: scottb, jbrosenberg,
Description:
Adds some more docs to TypeTightener and MethodCallTightener
Please review this at http://gwt-code-reviews.appspot.com/1447814/
Affected files:
M dev/core/src/com/google/gwt/dev/jjs/impl/MethodCallTightener.java
M dev/core/src/com/google/gwt/dev/jjs/impl/TypeTightener.java
Index: dev/core/src/com/google/gwt/dev/jjs/impl/MethodCallTightener.java
===================================================================
--- dev/core/src/com/google/gwt/dev/jjs/impl/MethodCallTightener.java
(revision 10251)
+++ dev/core/src/com/google/gwt/dev/jjs/impl/MethodCallTightener.java
(working copy)
@@ -35,6 +35,17 @@
*
* This is possible because the qualifier might have been tightened by
* {@link com.google.gwt.dev.jjs.impl.TypeTightener}.
+ *
+ * For example, given the code:
+ *
+ * List foo = new ArrayList<String>();
+ *
+ * foo.add("bar");
+ *
+ * The type of foo is tightened by TypeTightener from type List to be of
type
+ * ArrayList. This means that MethodCallTightener can analyze the
polymorphic
+ * call List.add() on foo and tighten it to the more specific
ArrayList.add()
+ *
*/
public class MethodCallTightener {
/**
Index: dev/core/src/com/google/gwt/dev/jjs/impl/TypeTightener.java
===================================================================
--- dev/core/src/com/google/gwt/dev/jjs/impl/TypeTightener.java (revision
10251)
+++ dev/core/src/com/google/gwt/dev/jjs/impl/TypeTightener.java (working
copy)
@@ -71,6 +71,25 @@
* types can be inferred for locals, fields, parameters, and method return
* types. We also optimize dynamic casts and instanceof operations.
*
+ * Examples:
+ *
+ * This declaration of variable foo:
+ *
+ * final List foo = new ArrayList<String>();
+ *
+ * can be tightened from List to ArrayList because no type other than
ArrayList
+ * can ever assigned to foo.
+ *
+ * The return value of the method bar:
+ *
+ * Collection<String> bar() { return new LinkedHashSet<String>; }
+ *
+ * can be tightened from Collection<String> to LinkedHashSet<String> since
it
+ * will never return any other type.
+ *
+ * By working in conjunction with {@link MethodCallTightener}, Type
tightening can
+ * eliminate generating run-time dispatch code for polymorphic methods.
+ *
* Type flow occurs automatically in most JExpressions. But locals, fields,
* parameters, and method return types serve as "way points" where type
* information is fixed based on the declared type. Type tightening can be
done
--
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