Merge pull request #178 from /issues/177

Fixes #177 adds seqObj

Author: Brian Mock

API.md

@@ -178,13 +178,14 @@ Returns a parser that doesn't consume any input, and yields `result`.
 
 This is an alias for `Parsimmon.succeed(result)`.
 
+## Parsimmon.formatError(string, error)
+
+Takes the `string` passed to `parser.parse(string)` and the `error` returned from `parser.parse(string)` and turns it into a human readable error message string. Note that there are certainly better ways to format errors, so feel free to write your own.
+
 ## Parsimmon.seq(p1, p2, ...pn)
 
 Accepts any number of parsers and returns a new parser that expects them to match in order, yielding an array of all their results.
 
-## Parsimmon.formatError(string, error)
-
-Takes the `string` passed to `parser.parse(string)` and the `error` returned from `parser.parse(string)` and turns it into a human readable error message string. Note that there are certainly better ways to format errors, so feel free to write your own.
 
 ## Parsimmon.seqMap(p1, p2, ...pn, function(r1, r2, ...rn))
 
@@ -204,6 +205,38 @@ Parsimmon.seqMap(
 ).parse('a+x')
 ```
 
+## Parsimmon.seqObj(...args)
+
+Similar to `Parsimmon.seq(...parsers)`, but yields an object of results named based on arguments.
+
+Takes one or more arguments, where each argument is either a parser or a named parser pair (`[stringKey, parser]`).
+
+Requires at least one named parser.
+
+All named parser keys must be unique.
+
+Example:
+
+```js
+var _ = Parsimmon.optWhitespace;
+var identifier = Parsimmon.regexp(/[a-z_][a-z0-9_]*/i);
+var lparen = Parsimmon.string('(');
+var rparen = Parsimmon.string(')');
+var comma = Parsimmon.string(',');
+var functionCall =
+  Parsimmon.seqObj(
+    ['function', identifier],
+    lparen,
+    ['arguments', identifier.trim(_).sepBy(comma)],
+    rparen
+  );
+functionCall.tryParse('foo(bar, baz, quux)');
+// => { function: 'foo',
+//      arguments: [ 'bar', 'baz', 'quux' ] }
+```
+
+Tip: Combines well with `.node(name)` for a full-featured AST node.
+
 ## Parsimmon.alt(p1, p2, ...pn)
 
 Accepts any number of parsers, yielding the value of the first one that succeeds, backtracking in between.

CHANGELOG.md

@@ -1,5 +1,11 @@
+## version 1.6.0 (2017-06-26)
+
+* Adds `Parsimmon.seqObj(...args)`
+
 ## version 1.5.0 (2017-06-17)
 
+NOTE: Code was completed on 2017-06-17, but due to human error, was not published on npm until 2017-06-26.
+
 * Adds `parser.sepBy(separator)` alias for `Parsimmon.sepBy(parser, separator)`
 * Adds `parser.sepBy1(separator)` alias for `Parsimmon.sepBy1(parser, separator)`
 * Adds `Parsimmon.range(begin, end)`

examples/python-ish.js

@@ -51,14 +51,16 @@ let Pythonish = P.createLanguage({
   // block, and require that every other statement has the same exact string of
   // indentation in front of it.
   Block: r =>
-    P.seq(
-      P.string('block:\n').then(P.regexp(/[ ]+/)),
-      r.Statement
+    P.seqObj(
+      P.string('block:'),
+      P.string('\n'),
+      ['indent', P.regexp(/[ ]+/)],
+      ['statement', r.Statement]
     ).chain(args => {
       // `.chain` is called after a parser succeeds. It returns the next parser
       // to use for parsing. This allows subsequent parsing to be dependent on
       // previous text.
-      let [indent, statement] = args;
+      let {indent, statement} = args;
       let indentSize = indent.length;
       let currentSize = indentPeek();
       // Indentation must be deeper than the current block context. Otherwise

examples/seqobj.js

@@ -0,0 +1,44 @@
+'use strict';
+
+// Run me with Node to see my output!
+
+let util = require('util');
+let P = require('../');
+
+///////////////////////////////////////////////////////////////////////
+
+let Lang = P.createLanguage({
+
+  _: () => P.optWhitespace,
+
+  LParen: () => P.string('('),
+  RParen: () => P.string(')'),
+  Comma: () => P.string(','),
+  Dot: () => P.string('.'),
+
+  Identifier: () => P.letters.node('Identifier'),
+
+  MethodCall: r =>
+    P.seqObj(
+      ['receiver', r.Identifier],
+      r.Dot.trim(r._),
+      ['method', r.Identifier],
+      r.LParen,
+      ['arguments', r.Identifier.trim(r._).sepBy(r.Comma)],
+      r.RParen
+    ).node('MethodCall'),
+
+});
+
+///////////////////////////////////////////////////////////////////////
+
+let text = 'console.log(bar, baz, quux)';
+
+function prettyPrint(x) {
+  let opts = {depth: null, colors: 'auto'};
+  let s = util.inspect(x, opts);
+  console.log(s);
+}
+
+let ast = Lang.MethodCall.tryParse(text);
+prettyPrint(ast);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "parsimmon",
-  "version": "1.5.0",
+  "version": "1.6.0",
   "description": "A monadic LL(infinity) parser combinator library",
   "keywords": [
     "parsing",

src/parsimmon.js

@@ -15,6 +15,10 @@ function isParser(obj) {
   return obj instanceof Parsimmon;
 }
 
+function isArray(x) {
+  return {}.toString.call(x) === '[object Array]';
+}
+
 function makeSuccess(index, value) {
   return {
     status: true,
@@ -107,7 +111,7 @@ function assertParser(p) {
 
 // TODO[ES5]: Switch to Array.isArray eventually.
 function assertArray(x) {
-  if ({}.toString.call(x) !== '[object Array]') {
+  if (!isArray(x)) {
     throw new Error('not an array: ' + x);
   }
 }
@@ -203,6 +207,65 @@ function seq() {
   });
 }
 
+function seqObj() {
+  var seenKeys = {};
+  var totalKeys = 0;
+  var parsers = [].slice.call(arguments);
+  var numParsers = parsers.length;
+  for (var j = 0; j < numParsers; j += 1) {
+    var p = parsers[j];
+    if (isParser(p)) {
+      continue;
+    }
+    if (isArray(p)) {
+      var isWellFormed =
+        p.length === 2 &&
+        typeof p[0] === 'string' &&
+        isParser(p[1]);
+      if (isWellFormed) {
+        var key = p[0];
+        if (seenKeys[key]) {
+          throw new Error('seqObj: duplicate key ' + key);
+        }
+        seenKeys[key] = true;
+        totalKeys++;
+        continue;
+      }
+    }
+    throw new Error(
+      'seqObj arguments must be parsers or ' +
+      '[string, parser] array pairs.'
+    );
+  }
+  if (totalKeys === 0) {
+    throw new Error('seqObj expects at least one named parser, found zero');
+  }
+  return Parsimmon(function(input, i) {
+    var result;
+    var accum = {};
+    for (var j = 0; j < numParsers; j += 1) {
+      var name;
+      var parser;
+      if (isArray(parsers[j])) {
+        name = parsers[j][0];
+        parser = parsers[j][1];
+      } else {
+        name = null;
+        parser = parsers[j];
+      }
+      result = mergeReplies(parser._(input, i), result);
+      if (!result.status) {
+        return result;
+      }
+      if (name) {
+        accum[name] = result.value;
+      }
+      i = result.index;
+    }
+    return mergeReplies(makeSuccess(i, accum), result);
+  });
+}
+
 function seqMap() {
   var args = [].slice.call(arguments);
   if (args.length === 0) {
@@ -720,6 +783,7 @@ Parsimmon.sepBy = sepBy;
 Parsimmon.sepBy1 = sepBy1;
 Parsimmon.seq = seq;
 Parsimmon.seqMap = seqMap;
+Parsimmon.seqObj = seqObj;
 Parsimmon.string = string;
 Parsimmon.succeed = succeed;
 Parsimmon.takeWhile = takeWhile;

test/core/seqObj.test.js

@@ -0,0 +1,65 @@
+'use strict';
+
+suite('Parsimmon.seqObj', function() {
+
+  test('does not accept duplicate keys', function() {
+    assert.throws(function() {
+      Parsimmon.seqObj(
+        ['a', Parsimmon.of(1)],
+        ['b', Parsimmon.of(2)],
+        ['a', Parsimmon.of(3)]
+      );
+    });
+  });
+
+  test('requires at least one key', function() {
+    assert.throws(function() {
+      Parsimmon.seqObj();
+    });
+  });
+
+  test('every key is present in the result object', function() {
+    var parser = Parsimmon.seqObj(
+      ['a', Parsimmon.of(1)],
+      ['b', Parsimmon.of(2)],
+      ['c', Parsimmon.of(3)]
+    );
+    var result = parser.tryParse('');
+    assert.deepStrictEqual(result, {
+      a: 1,
+      b: 2,
+      c: 3,
+    });
+  });
+
+  test('every parser is used', function() {
+    var parser = Parsimmon.seqObj(
+      Parsimmon.string('a'),
+      ['b', Parsimmon.string('b')],
+      Parsimmon.string('c'),
+      ['d', Parsimmon.string('d')],
+      Parsimmon.string('e')
+    );
+    var result = parser.tryParse('abcde');
+    assert.deepStrictEqual(result, {
+      b: 'b',
+      d: 'd',
+    });
+  });
+
+  test('named parser arrays are formed properly', function() {
+    assert.throws(function() {
+      Parsimmon.seqObj([]);
+    });
+    assert.throws(function() {
+      Parsimmon.seqObj(['a', Parsimmon.of(1), 'oops extra']);
+    });
+    assert.throws(function() {
+      Parsimmon.seqObj([123, Parsimmon.of(1)]);
+    });
+    assert.throws(function() {
+      Parsimmon.seqObj(['cool', 'potato']);
+    });
+  });
+
+});