Merge pull request #541 from TalAter/conditional-improvements

Conditional assignment of equivalent constants compressed  ( x=y?1:1 --> x=1 )

2 files changed, 72 insertions, 0 deletions

diff --git a/lib/compress.js b/lib/compress.js
index b55361b3..77de5946 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -2321,6 +2321,17 @@ merge(Compressor.prototype, {
                 alternative: alternative
             });
         }
+        // x=y?1:1 --> x=1
+        if (consequent instanceof AST_Constant
+            && alternative instanceof AST_Constant
+            && consequent.equivalent_to(alternative)) {
+            if (self.condition.has_side_effects(compressor)) {
+                return AST_Seq.from_array([self.condition, make_node_from_constant(compressor, consequent.value, self)]);
+            } else {
+                return make_node_from_constant(compressor, consequent.value, self);
+
+            }
+        }
         return self;
     });
 
diff --git a/test/compress/conditionals.js b/test/compress/conditionals.js
index 213b246b..c20297aa 100644
--- a/test/compress/conditionals.js
+++ b/test/compress/conditionals.js
@@ -232,3 +232,64 @@ cond_5: {
         some_condition() && some_other_condition() && do_something();
     }
 }
+
+cond_7: {
+    options = {
+        conditionals: true,
+        evaluate    : true
+    };
+    input: {
+        // compress these
+        if (y) {
+            x = 1+1;
+        } else {
+            x = 2;
+        }
+
+        if (y) {
+            x = 1+1;
+        } else if (z) {
+            x = 2;
+        } else {
+            x = 3-1;
+        }
+
+        x = y ? 'foo' : 'fo'+'o';
+
+        x = y ? 'foo' : y ? 'foo' : 'fo'+'o';
+
+        // Compress conditions that have side effects
+        if (condition()) {
+            x = 10+10;
+        } else {
+            x = 20;
+        }
+
+        if (z) {
+            x = 'fuji';
+        } else if (condition()) {
+            x = 'fu'+'ji';
+        } else {
+            x = 'fuji';
+        }
+
+        x = condition() ? 'foobar' : 'foo'+'bar';
+
+        // don't compress these
+        x = y ? a : b;
+
+        x = y ? 'foo' : 'fo';
+    }
+    expect: {
+        x = 2;
+        x = 2;
+        x = 'foo';
+        x = 'foo';
+        x = (condition(), 20);
+        x = z ? 'fuji' : (condition(), 'fuji');
+        x = (condition(), 'foobar');
+        x = y ? a : b;
+        x = y ? 'foo' : 'fo';
+    }
+}
+