buffer: add indexOf method

Adds a `.indexOf` method to `Buffer`, which borrows semantics from both `Array.prototype.indexOf` and `String.prototype.indexOf`. `Buffer.prototype.indexOf` can be invoked with a Buffer, a string or a number as the needle. If the needle a Buffer or string, it will find the first occurrence of this sequence of bytes. If the needle is a number, it will find the first occurrence of this byte. Reviewed-by: Sam Rijs <[email protected]> Fixes: #95 PR-URL: #160
nodejs · algesten · Dec 14, 2014 · Dec 14, 2014 · Dec 14, 2014 · 4dedc0929472976e8730fd317b05a4eabf522f86
commit 4dedc0929472976e8730fd317b05a4eabf522f86
diff --git a/doc/api/buffer.markdown b/doc/api/buffer.markdown
@@ -764,6 +764,13 @@ buffer.
     var b = new Buffer(50);
     b.fill("h");
 
+### buf.indexOf(value[, fromIndex])
+
+* `value` Buffer or String or Number
+* `fromIndex` Number, Optional, Default: 0
+
+Finds the index within the buffer of the first occurrence of the specified value, starting the search at fromIndex. Returns -1 if the value is not found.
+
 ## buffer.INSPECT_MAX_BYTES
 
 * Number, Default: 50

diff --git a/lib/buffer.js b/lib/buffer.js
@@ -332,6 +332,16 @@ Buffer.prototype.fill = function fill(val, start, end) {
   return this;
 };
 
+Buffer.prototype.indexOf = function indexOf(needle, pos) {
+  if (typeof needle === 'number') {
+    needle = new Buffer([needle]);
+  } else if (typeof needle === 'string') {
+    needle = new Buffer(needle);
+  } else if (!(needle instanceof Buffer)) {
+    throw new TypeError('Argument must be a Buffer, number or string');
+  }
+  return internal.indexOf(this, needle, pos);
+};
 
 // XXX remove in v0.13
 Buffer.prototype.get = util.deprecate(function get(offset) {

diff --git a/src/node_buffer.cc b/src/node_buffer.cc
@@ -34,6 +34,7 @@
 #include <limits.h>
 
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
 
 #define CHECK_NOT_OOB(r)                                                    \
   do {                                                                      \
@@ -585,6 +586,54 @@ void Compare(const FunctionCallbackInfo<Value> &args) {
   args.GetReturnValue().Set(val);
 }
 
+void IndexOf(const FunctionCallbackInfo<Value> &args) {
+  Local<Object> obj = args[0]->ToObject();
+  char* obj_data =
+      static_cast<char*>(obj->GetIndexedPropertiesExternalArrayData());
+  int32_t obj_length = obj->GetIndexedPropertiesExternalArrayDataLength();
+
+  Local<Object> search = args[1]->ToObject();
+  char* search_data =
+    static_cast<char*>(search->GetIndexedPropertiesExternalArrayData());
+  int32_t search_length = search->GetIndexedPropertiesExternalArrayDataLength();
+
+  int32_t pos = args[2]->Int32Value();
+  int32_t start = MIN(MAX(pos, 0), obj_length);
+
+  if (search_length == 0) {
+    return args.GetReturnValue().Set(start);
+  }
+
+  while (search_length <= obj_length - start) {
+    // Search for the first byte of the needle.
+    char *chr = reinterpret_cast<char *>(
+        memchr(&obj_data[start], search_data[0], obj_length - start));
+    int32_t chrpos = (intptr_t)chr - (intptr_t)obj_data;
+    if (chr == NULL) {
+      // First byte not found, short circuit.
+      return args.GetReturnValue().Set(-1);
+    }
+    if (search_length == 1) {
+      // Nothing more to compare, we found it.
+      return args.GetReturnValue().Set(chrpos);
+    }
+    if (search_length > obj_length - chrpos) {
+      // Needle is longer than the rest of the haystack,
+      // no way it is contained in there.
+      return args.GetReturnValue().Set(-1);
+    }
+    int cmp = memcmp(&chr[1], &search_data[1], search_length - 1);
+    if (cmp == 0) {
+      // All bytes are equal, we found it.
+      return args.GetReturnValue().Set(chrpos);
+    }
+    // Advance start position for next iteration.
+    start = chrpos + 1;
+  }
+
+  return args.GetReturnValue().Set(-1);
+}
+
 
 // pass Buffer object to load prototype methods
 void SetupBufferJS(const FunctionCallbackInfo<Value>& args) {
@@ -629,6 +678,7 @@ void SetupBufferJS(const FunctionCallbackInfo<Value>& args) {
   env->SetMethod(internal, "byteLength", ByteLength);
   env->SetMethod(internal, "compare", Compare);
   env->SetMethod(internal, "fill", Fill);
+  env->SetMethod(internal, "indexOf", IndexOf);
 
   env->SetMethod(internal, "readDoubleBE", ReadDoubleBE);
   env->SetMethod(internal, "readDoubleLE", ReadDoubleLE);

diff --git a/test/simple/test-buffer.js b/test/simple/test-buffer.js
@@ -1184,3 +1184,13 @@ assert.throws(function() {
   var b = new Buffer(1);
   b.equals('abc');
 });
+
+// IndexOf Tests
+assert.equal(Buffer('abc').indexOf(''), 0)
+assert.equal(Buffer('abc').indexOf('bd'), -1)
+assert.equal(Buffer('abc').indexOf('bc'), 1)
+assert.equal(Buffer('abc').indexOf(0x62), 1)
+assert.equal(Buffer('abc').indexOf(Buffer('bc')), 1)
+assert.equal(Buffer('abc').indexOf(Buffer([0x62,0x63])), 1)
+assert.equal(Buffer('abc').indexOf('bc', 1), 1)
+assert.equal(Buffer('abc').indexOf('bc', 2), -1)