Add an option to escape forward slash character

Squashed commit of the following:

commit 26d181059989279a79c433cedcd893b4f52e42ee
Author: Francois Chagnon <francois.chagnon@jadedpixel.com>
Date:   Tue Sep 15 21:17:34 2015 +0000

    add config options for escape_slash

commit fa282334051b16df91ca097dd7304b46f3bc7719
Author: Francois Chagnon <francois.chagnon@jadedpixel.com>
Date:   Mon Feb 9 21:09:33 2015 +0000

    add forward slash to escape character

3 files changed, 39 insertions, 3 deletions

diff --git a/java/src/json/ext/Generator.java b/java/src/json/ext/Generator.java
index 24bf049..cd23c73 100644
--- a/java/src/json/ext/Generator.java
+++ b/java/src/json/ext/Generator.java
@@ -158,7 +158,7 @@ public final class Generator {
 
         public StringEncoder getStringEncoder() {
             if (stringEncoder == null) {
-                stringEncoder = new StringEncoder(context, getState().asciiOnly());
+                stringEncoder = new StringEncoder(context, getState().asciiOnly(), getState().escapeSlash());
             }
             return stringEncoder;
         }
diff --git a/java/src/json/ext/GeneratorState.java b/java/src/json/ext/GeneratorState.java
index 44a9311..7fec09d 100644
--- a/java/src/json/ext/GeneratorState.java
+++ b/java/src/json/ext/GeneratorState.java
@@ -83,6 +83,12 @@ public class GeneratorState extends RubyObject {
     private boolean quirksMode = DEFAULT_QUIRKS_MODE;
     static final boolean DEFAULT_QUIRKS_MODE = false;
     /**
+     * If set to <code>true</code> the forward slash will be escaped in
+     * json output.
+     */
+    private boolean escapeSlash = DEFAULT_ESCAPE_SLASH;
+    static final boolean DEFAULT_ESCAPE_SLASH = false;
+    /**
      * The initial buffer length of this state. (This isn't really used on all
      * non-C implementations.)
      */
@@ -171,6 +177,9 @@ public class GeneratorState extends RubyObject {
      * <code>-Infinity</code> should be generated, otherwise an exception is
      * thrown if these values are encountered.
      * This options defaults to <code>false</code>.
+     * <dt><code>:escape_slash</code>
+     * <dd>set to <code>true</code> if the forward slashes should be escaped
+     * in the json output (default: <code>false</code>)
      */
     @JRubyMethod(optional=1, visibility=Visibility.PRIVATE)
     public IRubyObject initialize(ThreadContext context, IRubyObject[] args) {
@@ -194,6 +203,7 @@ public class GeneratorState extends RubyObject {
         this.allowNaN = orig.allowNaN;
         this.asciiOnly = orig.asciiOnly;
         this.quirksMode = orig.quirksMode;
+        this.escapeSlash = orig.escapeSlash;
         this.bufferInitialLength = orig.bufferInitialLength;
         this.depth = orig.depth;
         return this;
@@ -346,6 +356,24 @@ public class GeneratorState extends RubyObject {
         return max_nesting;
     }
 
+    /**
+     * Returns true if forward slashes are escaped in the json output.
+     */
+    public boolean escapeSlash() {
+        return escapeSlash;
+    }
+
+    @JRubyMethod(name="escape_slash")
+    public RubyBoolean escape_slash_get(ThreadContext context) {
+        return context.getRuntime().newBoolean(escapeSlash);
+    }
+
+    @JRubyMethod(name="escape_slash=")
+    public IRubyObject escape_slash_set(IRubyObject escape_slash) {
+        escapeSlash = escape_slash.isTrue();
+        return escape_slash.getRuntime().newBoolean(escapeSlash);
+    }
+
     public boolean allowNaN() {
         return allowNaN;
     }
@@ -430,6 +458,7 @@ public class GeneratorState extends RubyObject {
         maxNesting = opts.getInt("max_nesting", DEFAULT_MAX_NESTING);
         allowNaN   = opts.getBool("allow_nan",  DEFAULT_ALLOW_NAN);
         asciiOnly  = opts.getBool("ascii_only", DEFAULT_ASCII_ONLY);
+        escapeSlash = opts.getBool("escape_slash", DEFAULT_ESCAPE_SLASH);
         bufferInitialLength = opts.getInt("buffer_initial_length", DEFAULT_BUFFER_INITIAL_LENGTH);
 
         depth = opts.getInt("depth", 0);
@@ -457,6 +486,7 @@ public class GeneratorState extends RubyObject {
         result.op_aset(context, runtime.newSymbol("allow_nan"), allow_nan_p(context));
         result.op_aset(context, runtime.newSymbol("ascii_only"), ascii_only_p(context));
         result.op_aset(context, runtime.newSymbol("max_nesting"), max_nesting_get(context));
+        result.op_aset(context, runtime.newSymbol("escape_slash"), escape_slash_get(context));
         result.op_aset(context, runtime.newSymbol("depth"), depth_get(context));
         result.op_aset(context, runtime.newSymbol("buffer_initial_length"), buffer_initial_length_get(context));
         for (String name: getInstanceVariableNameList()) {
diff --git a/java/src/json/ext/StringEncoder.java b/java/src/json/ext/StringEncoder.java
index 9d40dd3..26678ed 100644
--- a/java/src/json/ext/StringEncoder.java
+++ b/java/src/json/ext/StringEncoder.java
@@ -15,7 +15,7 @@ import org.jruby.util.ByteList;
  * and throws a GeneratorError if any problem is found.
  */
 final class StringEncoder extends ByteListTranscoder {
-    private final boolean asciiOnly;
+    private final boolean asciiOnly, escapeSlash;
 
     // Escaped characters will reuse this array, to avoid new allocations
     // or appending them byte-by-byte
@@ -37,9 +37,10 @@ final class StringEncoder extends ByteListTranscoder {
             new byte[] {'0', '1', '2', '3', '4', '5', '6', '7',
                         '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
 
-    StringEncoder(ThreadContext context, boolean asciiOnly) {
+    StringEncoder(ThreadContext context, boolean asciiOnly, boolean escapeSlash) {
         super(context);
         this.asciiOnly = asciiOnly;
+        this.escapeSlash = escapeSlash;
     }
 
     void encode(ByteList src, ByteList out) {
@@ -73,6 +74,11 @@ final class StringEncoder extends ByteListTranscoder {
         case '\b':
             escapeChar('b');
             break;
+        case '/':
+            if(escapeSlash) {
+                escapeChar((char)c);
+                break;
+            }
         default:
             if (c >= 0x20 && c <= 0x7f ||
                     (c >= 0x80 && !asciiOnly)) {