Minify boolean and numeric literals in obfuscated mode

Author: zbynek

dev/core/src/com/google/gwt/dev/jjs/JavaToJavaScriptCompiler.java

@@ -151,6 +151,7 @@
 import com.google.gwt.dev.js.JsStackEmulator;
 import com.google.gwt.dev.js.JsStaticEval;
 import com.google.gwt.dev.js.JsSymbolResolver;
+import com.google.gwt.dev.js.JsToStringGenerationVisitor;
 import com.google.gwt.dev.js.JsUnusedFunctionRemover;
 import com.google.gwt.dev.js.JsVerboseNamer;
 import com.google.gwt.dev.js.SizeBreakdown;
@@ -772,7 +773,9 @@ private void generateJavaScriptCode(JavaToJavaScriptMap jjsMap, String[] jsFragm
           DefaultTextOutput out = new DefaultTextOutput(!options.isIncrementalCompileEnabled() &&
               options.getOutput().shouldMinimize());
           JsReportGenerationVisitor v = new JsReportGenerationVisitor(out, jjsMap,
-              options.isJsonSoycEnabled());
+              options.isJsonSoycEnabled(),
+              new JsToStringGenerationVisitor.PrintOptions(false,
+                  options.getOutput() == JsOutputOption.DETAILED));
           v.accept(jsProgram.getFragmentBlock(i));
 
           StatementRanges statementRanges = v.getStatementRanges();

dev/core/src/com/google/gwt/dev/js/JsReportGenerationVisitor.java

@@ -56,8 +56,8 @@ public class JsReportGenerationVisitor extends
   private List<JsNode> parentStack = Lists.newArrayList();
 
   public JsReportGenerationVisitor(TextOutput out, JavaToJavaScriptMap map,
-      boolean needSourcemapNames) {
-    super(out, map);
+      boolean needSourcemapNames, PrintOptions options) {
+    super(out, map, options);
     this.out = out;
     this.needSourcemapNames = needSourcemapNames;
   }

dev/core/src/com/google/gwt/dev/js/JsSourceGenerationVisitor.java

@@ -36,10 +36,10 @@ public JsSourceGenerationVisitor(TextOutput out) {
   /**
    * Generate the output source code using short or long identifiers.
    *
-   * @param useLongIdents if true, emit all identifiers in long form
+   * @param options minification options
    */
-  public JsSourceGenerationVisitor(TextOutput out, boolean useLongIdents) {
-    super(out, useLongIdents);
+  public JsSourceGenerationVisitor(TextOutput out, PrintOptions options) {
+    super(out, options);
   }
 
   @Override

dev/core/src/com/google/gwt/dev/js/JsSourceGenerationVisitorWithSizeBreakdown.java

@@ -40,8 +40,8 @@ public class JsSourceGenerationVisitorWithSizeBreakdown extends JsSourceGenerati
   private final Map<JsName, Integer> sizeMap = new HashMap<JsName, Integer>();
 
   public JsSourceGenerationVisitorWithSizeBreakdown(TextOutput out,
-      JavaToJavaScriptMap javaToJavaScriptMap) {
-    super(out);
+      JavaToJavaScriptMap javaToJavaScriptMap, PrintOptions options) {
+    super(out, options);
     this.out = out;
     this.map = javaToJavaScriptMap;
   }

dev/core/src/com/google/gwt/dev/js/JsToStringGenerationVisitor.java

@@ -115,9 +115,10 @@ public class JsToStringGenerationVisitor extends JsVisitor {
    * How many lines of code to print inside of a JsBlock when printing terse.
    */
   private static final int JSBLOCK_LINES_TO_PRINT = 3;
+  private static final long MAX_DECIMAL_VALUE = 999_999_999_999L;
 
   protected boolean needSemi = true;
-  private List<NamedRange> classRanges = new ArrayList<NamedRange>();
+  private final List<NamedRange> classRanges = new ArrayList<>();
   private NamedRange currentClassRange;
   private NamedRange programClassRange;
 
@@ -127,27 +128,39 @@ public class JsToStringGenerationVisitor extends JsVisitor {
    * because the statements designated by statementEnds and statementStarts are
    * those that appear directly within these global blocks.
    */
-  private Set<JsBlock> globalBlocks = new HashSet<JsBlock>();
+  private final Set<JsBlock> globalBlocks = new HashSet<>();
   private final TextOutput p;
-  private ArrayList<Integer> statementEnds = new ArrayList<Integer>();
-  private ArrayList<Integer> statementStarts = new ArrayList<Integer>();
+  private final ArrayList<Integer> statementEnds = new ArrayList<>();
+  private final ArrayList<Integer> statementStarts = new ArrayList<>();
   private final boolean useLongIdents;
+  private final boolean minifyLiterals;
+
+  public static class PrintOptions {
+    public final boolean useLongIdents;
+    public final boolean minifyLiterals;
+
+    public PrintOptions(boolean useLongIdents, boolean minifyLiterals) {
+      this.useLongIdents = useLongIdents;
+      this.minifyLiterals = minifyLiterals;
+    }
+  }
 
   /**
    * Generate the output string using short identifiers.
    */
   public JsToStringGenerationVisitor(TextOutput out) {
-    this(out, false);
+    this(out, new PrintOptions(false, false));
   }
 
   /**
    * Generate the output string using short or long identifiers.
    *
-   * @param useLongIdents if true, emit all identifiers in long form
+   * @param options settings for minification
    */
-  JsToStringGenerationVisitor(TextOutput out, boolean useLongIdents) {
+  JsToStringGenerationVisitor(TextOutput out, PrintOptions options) {
     this.p = out;
-    this.useLongIdents = useLongIdents;
+    this.useLongIdents = options.useLongIdents;
+    this.minifyLiterals = options.minifyLiterals;
   }
 
   public List<NamedRange> getClassRanges() {
@@ -183,8 +196,7 @@ public boolean visit(JsArrayAccess x, JsContext ctx) {
   public boolean visit(JsArrayLiteral x, JsContext ctx) {
     _lsquare();
     boolean sep = false;
-    for (Object element : x.getExpressions()) {
-      JsExpression arg = (JsExpression) element;
+    for (JsExpression arg : x.getExpressions()) {
       sep = _sepCommaOptSpace(sep);
       _parenPushIfCommaExpr(arg);
       accept(arg);
@@ -227,6 +239,10 @@ public boolean visit(JsBlock x, JsContext ctx) {
 
   @Override
   public boolean visit(JsBooleanLiteral x, JsContext ctx) {
+    if (minifyLiterals) {
+      p.print(x.getValue() ? "!0" : "!1");
+      return false;
+    }
     if (x.getValue()) {
       _true();
     } else {
@@ -257,8 +273,7 @@ public boolean visit(JsCase x, JsContext ctx) {
     _newlineOpt();
 
     indent();
-    for (Object element : x.getStmts()) {
-      JsStatement stmt = (JsStatement) element;
+    for (JsStatement stmt : x.getStmts()) {
       needSemi = true;
       accept(stmt);
       if (needSemi) {
@@ -387,8 +402,7 @@ public boolean visit(JsDefault x, JsContext ctx) {
     _colon();
 
     indent();
-    for (Object element : x.getStmts()) {
-      JsStatement stmt = (JsStatement) element;
+    for (JsStatement stmt : x.getStmts()) {
       needSemi = true;
       accept(stmt);
       if (needSemi) {
@@ -532,8 +546,7 @@ public boolean visit(JsFunction x, JsContext ctx) {
 
     _lparen();
     boolean sep = false;
-    for (Object element : x.getParameters()) {
-      JsParameter param = (JsParameter) element;
+    for (JsParameter param : x.getParameters()) {
       sep = _sepCommaOptSpace(sep);
       accept(param);
     }
@@ -588,8 +601,7 @@ public boolean visit(JsInvocation x, JsContext ctx) {
 
     _lparen();
     boolean sep = false;
-    for (Object element : x.getArguments()) {
-      JsExpression arg = (JsExpression) element;
+    for (JsExpression arg : x.getArguments()) {
       sep = _sepCommaOptSpace(sep);
       _parenPushIfCommaExpr(arg);
       accept(arg);
@@ -626,7 +638,7 @@ public boolean visit(JsNameRef x, JsContext ctx) {
       _parenPush(x, q, false);
       accept(q);
       if (q instanceof JsNumberLiteral) {
-        /**
+        /*
          * Fix for Issue #3796. "42.foo" is not allowed, but "42 .foo" is.
          */
         _space();
@@ -690,13 +702,40 @@ public boolean visit(JsNumberLiteral x, JsContext ctx) {
 
     long lvalue = (long) dvalue;
     if (lvalue == dvalue) {
-      p.print(Long.toString(lvalue));
+      String longVal = Long.toString(lvalue);
+      if (minifyLiterals && lvalue != 0) {
+        int trailingZeros = numberOfTrailingDecZeros(longVal);
+        if (trailingZeros > 2) {
+          // print 1000 as 1e3, keep 100 as is
+          longVal = longVal.substring(0, longVal.length() - trailingZeros) + "e" + trailingZeros;
+        } else if (Math.abs(lvalue) > MAX_DECIMAL_VALUE) {
+          // from 1e12 we may save 1 or 2 bytes by using the hex code
+          longVal = (lvalue < 0 ? "-0x" : "0x") + Long.toString(Math.abs(lvalue), 16);
+        }
+      }
+      p.print(longVal);
     } else {
-      p.print(Double.toString(dvalue));
+      String doubleVal = Double.toString(dvalue);
+      if (minifyLiterals) {
+        if (doubleVal.startsWith("0.")) {
+          doubleVal = doubleVal.substring(1);
+        } else if (doubleVal.startsWith("-0.")) {
+          doubleVal = "-" + doubleVal.substring(2);
+        }
+      }
+      p.print(doubleVal);
     }
     return false;
   }
 
+  private int numberOfTrailingDecZeros(String longVal) {
+    int idx = longVal.length() - 1;
+    while (longVal.charAt(idx) == '0') {
+      idx--;
+    }
+    return longVal.length() - idx - 1;
+  }
+
   @Override
   public boolean visit(JsNumericEntry x, JsContext ctx) {
     p.print(Integer.toString(x.getValue()));
@@ -790,7 +829,11 @@ public boolean visit(JsReturn x, JsContext ctx) {
     _return();
     JsExpression expr = x.getExpr();
     if (expr != null) {
-      _space();
+      if (spaceReturn(expr)) {
+        _space();
+      } else {
+        _spaceOpt();
+      }
       accept(expr);
     }
     return false;
@@ -1275,6 +1318,20 @@ private boolean _spaceCalc(JsOperator op, JsExpression arg) {
     return false;
   }
 
+  private boolean spaceReturn(JsExpression arg) {
+    if (arg instanceof JsBooleanLiteral) {
+      return !minifyLiterals;
+    }
+    if (arg instanceof JsPrefixOperation) {
+     return ((JsPrefixOperation) arg).getOperator().isKeyword();
+    }
+    if (arg instanceof JsNumberLiteral) {
+      double value = ((JsNumberLiteral) arg).getValue();
+      return Double.isNaN(value) || value > 0 || 1 / value > 0;
+    }
+    return true;
+  }
+
   private void _spaceOpt() {
     p.printOpt(' ');
   }

dev/core/src/com/google/gwt/dev/js/ast/JsNode.java

@@ -59,7 +59,8 @@ public final String toSource() {
    */
   public final String toSource(boolean useLongIdents) {
     DefaultTextOutput out = new DefaultTextOutput(false);
-    JsSourceGenerationVisitor v = new JsSourceGenerationVisitor(out, useLongIdents);
+    JsSourceGenerationVisitor v = new JsSourceGenerationVisitor(out,
+        new JsToStringGenerationVisitor.PrintOptions(useLongIdents, false));
     v.accept(this);
     return out.toString();
   }

dev/core/src/com/google/gwt/dev/util/AbstractTextOutput.java

@@ -73,11 +73,7 @@ public void indentOut() {
 
   @Override
   public void newline() {
-    if (compact) {
-      out.print('\n');
-    } else {
-      out.print('\n');
-    }
+    out.print('\n');
     position++;
     line++;
     column = 0;

dev/core/test/com/google/gwt/dev/js/JsReportGenerationVisitorTest.java

@@ -253,7 +253,8 @@ private void checkMappings(String ...expectedLines)
       throws IOException, JsParserException {
     DefaultTextOutput text = new DefaultTextOutput(compact);
     JsReportGenerationVisitor generator = new JsReportGenerationVisitor(text,
-        JavaToJavaScriptMap.EMPTY, false) {
+        JavaToJavaScriptMap.EMPTY, false,
+        new JsToStringGenerationVisitor.PrintOptions(false, false)) {
       @Override
       boolean surroundsInJavaSource(SourceInfo parent, SourceInfo child) {
         // The Rhino-based JavaScript parser doesn't provide character ranges