Add option to preserve/enforce string quote style

`-q 0` (default) use single or double quotes such as to minimize the number of
 bytes (prefers double quotes when both will do); this is the previous
 behavior.

`-q 1` -- always use single quotes

`-q 2` -- always use double quotes

`-q 3` or just `-q` -- always use the original quotes.

Related codegen option: `quote_style`.

Close #495
Close #460

Some `yargs` guru please tell me why `uglifyjs --help` doesn't display the
help string for `-q` / `--quotes`, and why it doesn't output the expected
argument types anymore, like good old `optimist` did.

1 files changed, 25 insertions, 9 deletions

diff --git a/lib/output.js b/lib/output.js
index bfe6242a..135636b9 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -63,6 +63,7 @@ function OutputStream(options) {
         preserve_line    : false,
         screw_ie8        : false,
         preamble         : null,
+        quote_style      : 0
     }, true);
 
     var indentation = 0;
@@ -84,7 +85,7 @@ function OutputStream(options) {
         });
     };
 
-    function make_string(str) {
+    function make_string(str, quote) {
         var dq = 0, sq = 0;
         str = str.replace(/[\\\b\f\n\r\t\x22\x27\u2028\u2029\0\ufeff]/g, function(s){
             switch (s) {
@@ -102,13 +103,27 @@ function OutputStream(options) {
             }
             return s;
         });
+        function quote_single() {
+            return "'" + str.replace(/\x27/g, "\\'") + "'";
+        }
+        function quote_double() {
+            return '"' + str.replace(/\x22/g, '\\"') + '"';
+        }
         if (options.ascii_only) str = to_ascii(str);
-        if (dq > sq) return "'" + str.replace(/\x27/g, "\\'") + "'";
-        else return '"' + str.replace(/\x22/g, '\\"') + '"';
+        switch (options.quote_style) {
+          case 1:
+            return quote_single();
+          case 2:
+            return quote_double();
+          case 3:
+            return quote == "'" ? quote_single() : quote_double();
+          default:
+            return dq > sq ? quote_single() : quote_double();
+        }
     };
 
-    function encode_string(str) {
-        var ret = make_string(str);
+    function encode_string(str, quote) {
+        var ret = make_string(str, quote);
         if (options.inline_script)
             ret = ret.replace(/<\x2fscript([>\/\t\n\f\r ])/gi, "<\\/script$1");
         return ret;
@@ -324,7 +339,7 @@ function OutputStream(options) {
         force_semicolon : force_semicolon,
         to_ascii        : to_ascii,
         print_name      : function(name) { print(make_name(name)) },
-        print_string    : function(str) { print(encode_string(str)) },
+        print_string    : function(str, quote) { print(encode_string(str, quote)) },
         next_indent     : next_indent,
         with_indent     : with_indent,
         with_block      : with_block,
@@ -581,7 +596,7 @@ function OutputStream(options) {
     /* -----[ PRINTERS ]----- */
 
     DEFPRINT(AST_Directive, function(self, output){
-        output.print_string(self.value);
+        output.print_string(self.value, self.quote);
         output.semicolon();
     });
     DEFPRINT(AST_Debugger, function(self, output){
@@ -1077,6 +1092,7 @@ function OutputStream(options) {
     });
     DEFPRINT(AST_ObjectKeyVal, function(self, output){
         var key = self.key;
+        var quote = self.quote;
         if (output.option("quote_keys")) {
             output.print_string(key + "");
         } else if ((typeof key == "number"
@@ -1087,7 +1103,7 @@ function OutputStream(options) {
         } else if (RESERVED_WORDS(key) ? output.option("screw_ie8") : is_identifier_string(key)) {
             output.print_name(key);
         } else {
-            output.print_string(key);
+            output.print_string(key, quote);
         }
         output.colon();
         self.value.print(output);
@@ -1125,7 +1141,7 @@ function OutputStream(options) {
         output.print(self.getValue());
     });
     DEFPRINT(AST_String, function(self, output){
-        output.print_string(self.getValue());
+        output.print_string(self.getValue(), self.quote);
     });
     DEFPRINT(AST_Number, function(self, output){
         output.print(make_num(self.getValue()));