Added "trim" and "padding" options for strings

Author: Ericbla

README.md

@@ -174,6 +174,10 @@ the following keys:
 - `stripNull` - (Optional, must be used with `length`) If true, then strip
   null characters from end of the string. (Note: has no effect on encoding, but
   when used, then the parse() and encode() functions are not the exact opposite)
+- `trim` - (Optional, default to `false`) If true, then trim() (remove leading and trailing spaces)
+  the parsed string.
+- `padding` - (Optional, Only used for encoding, default to `right`) If `left` then the string
+  will be right aligned (padding left with leading spaces) depending of the `length` option
 
 ### buffer(name[, options])
 Parse bytes as a buffer. `name` should consist only of alpha numeric

lib/binary_parser.js

@@ -758,6 +758,9 @@ Parser.prototype.generateString = function(ctx) {
   if (this.options.stripNull) {
     ctx.pushCode("{0} = {0}.replace(/\\x00+$/g, '')", name);
   }
+  if (this.options.trim) {
+    ctx.pushCode("{0} = {0}.trim()", name);
+  }
 };
 
 Parser.prototype.generate_encodeString = function(ctx) {
@@ -780,13 +783,22 @@ Parser.prototype.generate_encodeString = function(ctx) {
     // Compute padding length
     var padLen = ctx.generateTmpVariable();
     ctx.pushCode("{0} = {1} - {2}.length;", padLen, optLength, tmpBuf);
+    if (this.options.padding === "left") {
+      // Add heading padding spaces
+      ctx.pushCode(
+        "if ({0} > 0) {smartBuffer.writeString(' '.repeat({0}));}",
+        padLen
+      );
+    }
     // Copy the temporary string buffer to current smartBuffer
     ctx.pushCode("smartBuffer.writeBuffer({0});", tmpBuf);
-    // Add padding spaces
-    ctx.pushCode(
-      "if ({0} > 0) {smartBuffer.writeString(' '.repeat({0}));}",
-      padLen
-    );
+    if (this.options.padding !== "left") {
+      // Add trailing padding spaces
+      ctx.pushCode(
+        "if ({0} > 0) {smartBuffer.writeString(' '.repeat({0}));}",
+        padLen
+      );
+    }
   } else {
     ctx.pushCode(
       "smartBuffer.writeString({0}, '{1}');",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "binary-parser-encoder",
-  "version": "1.4.0",
+  "version": "1.4.1",
   "description": "Blazing-fast binary parser builder",
   "main": "lib/binary_parser.js",
   "devDependencies": {

test/primitive_parser.js

@@ -312,6 +312,19 @@ describe("Primitive parser", function() {
         a: "abc\u0000defghij\u0000"
       });
     });
+    it("should parse string and trim content", function() {
+      var buffer1 = Buffer.from("   abcd");
+      var buffer2 = Buffer.from("abcd   ");
+      var buffer3 = Buffer.from("  abcd ");
+      var parser = Parser.start().string("a", { length: 7, trim: true });
+      var result = {
+        a: "abcd"
+      };
+
+      assert.deepEqual(parser.parse(buffer1), result);
+      assert.deepEqual(parser.parse(buffer2), result);
+      assert.deepEqual(parser.parse(buffer3), result);
+    });
   });
 
   describe("Buffer parser", function() {

test/yy_primitive_encoder.js

@@ -360,6 +360,20 @@ describe("Primitive encoder", function() {
       var encoded = parser.encode(decoded);
       assert.deepEqual(encoded, buffer);
     });
+    it("should encode string with default right padding", function() {
+      var parser = Parser.start().string("a", { length: 6 });
+      var encoded = parser.encode({ a: "abcd" });
+      assert.deepEqual(encoded, Buffer.from("abcd  "));
+      encoded = parser.encode({ a: "abcdefgh" });
+      assert.deepEqual(encoded, Buffer.from("abcdef"));
+    });
+    it("should encode string with left padding", function() {
+      var parser = Parser.start().string("a", { length: 6, padding: "left" });
+      var encoded = parser.encode({ a: "abcd" });
+      assert.deepEqual(encoded, Buffer.from("  abcd"));
+      encoded = parser.encode({ a: "abcdefgh" });
+      assert.deepEqual(encoded, Buffer.from("abcdef"));
+    });
   });
 
   describe("Buffer encoder", function() {