Fixes keichi#16 Encding empty array

Author: Ericbla

lib/binary_parser.js

@@ -765,7 +765,6 @@ Parser.prototype.generateString = function(ctx) {
 
 Parser.prototype.generate_encodeString = function(ctx) {
   var name = ctx.generateVariable(this.varName);
-  var maxLen = ctx.generateTmpVariable();
 
   // Get the length of string to encode
   if (this.options.length) {
@@ -916,18 +915,14 @@ Parser.prototype.generate_encodeArray = function(ctx) {
     ctx.generateError('"Encoding associative array not supported"');
   }
 
+  ctx.pushCode("var {0} = 0;", maxItems);
+
+  // Get default array length (if defined)
+  ctx.pushCode("if({0}) {{1} = {0}.length;}", name, maxItems);
+
   // Compute the desired count of array items to encode (min of array size and length option)
   if (length !== undefined) {
-    var tmpLength = ctx.generateTmpVariable();
-    ctx.pushCode("var {0} = {1};", tmpLength, length);
-    ctx.pushCode(
-      "var {0} = {1}.length > {2} ? {2} : {1}.length;",
-      maxItems,
-      name,
-      tmpLength
-    );
-  } else {
-    ctx.pushCode("var {0} = {1}.length;", maxItems, name);
+    ctx.pushCode("{0} = {0} > {1} ? {1} : {0};", maxItems, length);
   }
 
   // Save current encoding smartBuffer and allocate a new one
@@ -938,6 +933,8 @@ Parser.prototype.generate_encodeArray = function(ctx) {
     this.smartBufferSize
   );
 
+  ctx.pushCode("if({0} > 0) { ", maxItems);
+
   ctx.pushCode("var {0} = 0;", itemCounter);
   if (
     typeof this.options.encodeUntil === "function" ||
@@ -990,6 +987,7 @@ Parser.prototype.generate_encodeArray = function(ctx) {
       savSmartBuffer
     );
   }
+  ctx.pushCode("}"); // End of 'if(...) {'
 
   var tmpBuffer = ctx.generateTmpVariable();
   ctx.pushCode("var {0} = smartBuffer.toBuffer()", tmpBuffer);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "binary-parser-encoder",
-  "version": "1.4.2",
+  "version": "1.4.3",
   "description": "Blazing-fast binary parser builder",
   "main": "lib/binary_parser.js",
   "devDependencies": {

test/zz_encoder_bugs.js

@@ -160,5 +160,63 @@ describe("Specific bugs testing", function() {
       var encoded = parser.encode(decoded);
       assert.deepEqual(encoded, Buffer.from("01020304050607", "hex"));
     });
+
+    it("should accept empty array to encode", function() {
+      var parser = Parser.start().array("arr", {
+        type: "uint8",
+        readUntil: "eof" // Read until end of buffer
+      });
+
+      var buffer = Buffer.from("", "hex");
+      var decoded = parser.parse(buffer);
+
+      assert.deepEqual(decoded, {
+        arr: []
+      });
+
+      var encoded = parser.encode(decoded);
+      assert.deepEqual(encoded, Buffer.from("", "hex"));
+    });
+
+    it("should accept empty array to encode and encodeUntil function", function() {
+      var parser = Parser.start().array("arr", {
+        type: "uint8",
+        readUntil: "eof", // Read until end of buffer
+        encodeUntil: function(item, obj) {
+          return false; // Never stop on content value
+        }
+      });
+
+      var buffer = Buffer.from("", "hex");
+      var decoded = parser.parse(buffer);
+
+      assert.deepEqual(decoded, {
+        arr: []
+      });
+
+      var encoded = parser.encode(decoded);
+      assert.deepEqual(encoded, Buffer.from("", "hex"));
+    });
+
+    it("should accept undefined or null array", function() {
+      var parser = Parser.start().array("arr", {
+        type: "uint8",
+        readUntil: "eof" // Read until end of buffer
+      });
+
+      var buffer = Buffer.from("", "hex");
+      var decoded = parser.parse(buffer);
+
+      // Decode an empty buffer as an empty array
+      assert.deepEqual(decoded, {
+        arr: []
+      });
+
+      // Encode undefined, null or empty array as an empty buffer
+      [{}, { arr: undefined }, { arr: null }, { arr: [] }].forEach(data => {
+        let encoded = parser.encode(data);
+        assert.deepEqual(encoded, Buffer.from("", "hex"));
+      });
+    });
   });
 });