Merge pull request #6 from axion014/minify-groups

Get rid of unnecessary grouping operators

Author: dhritzkiv

index.js

@@ -7,6 +7,9 @@ var lang = require('cssauron-glsl')
   , through = require('through')
   , shortest = require('shortest')
 
+// recognize commutative + but not * as these are conditional
+var commutative_operators = ['+', '&&', '||']
+
 function minifier(safe_words, mutate_storages) {
   safe_words = safe_words || ['main']
 
@@ -23,6 +26,18 @@ function minifier(safe_words, mutate_storages) {
   return through(mutate)
 
   function mutate(node) {
+    // remove unnecessary grouping operators
+    if(is_unnecessary_group(node)) return
+
+    if(node.parent) {
+      for(var current = node.parent; current.parent; current = current.parent) {
+        if(is_unnecessary_group(current)) {
+          current.parent.children[current.parent.children.indexOf(current)] = current.children[0]
+          current.children[0].parent = current.parent
+        }
+      }
+    }
+
     // vec2(1.0, 1.0) => vec2(1.0)
     if(node.parent && is_redundant_vector_literal(node.parent) && node.parent.children.indexOf(node) > 1) return
     if(is_redundant_vector_literal(node)) node.children = node.children.slice(0, 2)
@@ -56,6 +71,17 @@ function minifier(safe_words, mutate_storages) {
           !safe_words.hasOwnProperty(node.token.data)
   }
 
+  function is_unnecessary_group(node) {
+    if(node.type !== 'group') return false
+    if(node.children[0].lbp > node.parent.lbp) return true
+    if(node.children[0].lbp === node.parent.lbp) {
+      for(var i = 0; i < commutative_operators.length; i++) {
+        if(node.parent.data === commutative_operators[i] && node.children[0].data === commutative_operators[i]) return true
+      }
+    }
+    return false
+  }
+
   function is_redundant_vector_literal(node) {
     if(node.type === 'call' && /^[ib]?vec[234]$/.test(node.children[0].data) &&
       (node.children[1].type === 'literal' || node.children[1].type === 'ident')) {

tap-snapshots/test-basic.js-TAP.test.js

@@ -736,6 +736,14 @@ float f = .1;
 float g = .01;
 `
 
+exports[`test/basic.js TAP grouping removal test > output 1`] = `
+
+float a = 2e10 + .2e2 + 1.e3 * (0xFaBc09 + 3);
+float b = 2e10 + (.2e2 - 1.e3 / (0xFaBc09 + 3));
+bool c = 1. && true && true;
+bool d = 0. || false || true;
+`
+
 exports[`test/basic.js TAP vec shorthand > output 1`] = `
 
 vec2 vec2Long = vec2(.0, 1.);

test/basic.js

@@ -9,6 +9,7 @@ const path = require("path");
 const through = require("through");
 
 const zeroGLSL = path.resolve(__dirname, "./zero-decimals.glsl");
+const commutativeGLSL = path.resolve(__dirname, "./commutative-operators.glsl");
 const workingGLSL = path.resolve(__dirname, "./working.glsl");
 const vecGLSL = path.resolve(__dirname, "./vec-shorthand.glsl");
 
@@ -85,7 +86,7 @@ tap.test("decimals starting or ending with 0", t => {
 	fs.createReadStream(zeroGLSL)
 	.pipe(tokenizer())
 	.pipe(parser())
-	.pipe(minify(["main"], true))
+	.pipe(minify())
 	.pipe(deparser())
 	.pipe(endStream);
 });
@@ -137,3 +138,22 @@ tap.test("vec shorthand", t => {
 	.pipe(deparser())
 	.pipe(endStream);
 });
+
+tap.test("grouping removal test", t => {
+	let output = "";
+
+	const endStream = through((data) => {
+		output += data;
+	}, () => {
+		t.matchSnapshot(output, "output");
+		t.end();
+	});
+
+	fs.createReadStream(commutativeGLSL)
+	.pipe(tokenizer())
+	.pipe(parser())
+	.pipe(minify())
+	.pipe(deparser())
+	.pipe(endStream);
+});
+

test/commutative-operators.glsl

@@ -0,0 +1,6 @@
+float x = 2e10 + (.2e2 + (1.e3 * (0xFaBc09 + 3)));
+float y = 2e10 + (.2e2 - (1.e3 / (0xFaBc09 + 3)));
+
+bool a = 1. && (true && true);
+
+bool b = 0. || (false || true);

test/test.glsl

@@ -56,7 +56,7 @@ int first, second, third, fourth, fifth, sixth, seventh, eigth;
         vPosition = position;
         vec3 thing = vec2(1., 2.);
         int v_thing, garybusey;
-        thing.rgba = 2e10 + .2e2 + 1.e3 * 0xFaBc09 + (3 * v_thing);
+        thing.rgba = 2e10 + (.2e2 + (1.e3 * 0xFaBc09 + (3 * v_thing)));
 
         for(xxx i = 0; i < 10; ++i) {
           discard;