Accept a PostCSS Rule node as an input.

Author: ben-eb

API.md

@@ -612,11 +612,16 @@ var result = processor.process(' .class').result;
 // To have the parser normalize whitespace values, utilize the options
 var result = processor.process('  .class  ', {lossless: false}).result;
 // => .class
+
+// For better syntax errors, pass a PostCSS Rule node.
+var postcss = require('postcss');
+var rule = postcss.rule({selector: 'a'});
+var result = process.process(rule).result;
 ```
 
 Arguments:
 
-* `cssText (string)`: The css to be parsed.
+* `css (string|object)`: Either a selector string or a PostCSS Rule node.
 * `[options] (object)`: Process options
 
 Options:

src/__tests__/__snapshots__/postcss.js.md

@@ -0,0 +1,55 @@
+# Snapshot report for `src/__tests__/postcss.js`
+
+The actual snapshot is saved in `postcss.js.snap`.
+
+Generated by [AVA](https://ava.li).
+
+## missing open parenthesis
+
+> Snapshot 1
+
+    `CssSyntaxError: <css input>:1:6: Expected an opening parenthesis.␊
+    ␊
+    > 1 | a b c) {}␊
+        |      ^␊
+    `
+
+## missing open square bracket
+
+> Snapshot 1
+
+    `CssSyntaxError: <css input>:1:6: Expected an opening square bracket.␊
+    ␊
+    > 1 | a b c] {}␊
+        |      ^␊
+    `
+
+## missing pseudo class or pseudo element
+
+> Snapshot 1
+
+    `CssSyntaxError: <css input>:1:6: Expected a pseudo-class or pseudo-element.␊
+    ␊
+    > 1 | a b c: {}␊
+        |      ^␊
+    `
+
+## space in between colon and word (incorrect pseudo)
+
+> Snapshot 1
+
+    `CssSyntaxError: <css input>:1:5: Expected a pseudo-class or pseudo-element.␊
+    ␊
+    > 1 | a b: c {}␊
+        |     ^␊
+    `
+
+## string after colon (incorrect pseudo)
+
+> Snapshot 1
+
+    `CssSyntaxError: <css input>:1:5: Expected a pseudo-class or pseudo-element.␊
+    ␊
+    > 1 | a b:"wow" {}␊
+        |     ^␊
+    `

src/__tests__/__snapshots__/postcss.js.snap

@@ -0,0 +1,19 @@
+import test from 'ava';
+import postcss from 'postcss';
+import {parse} from './util/helpers';
+
+function showCode (t, selector) {
+    const rule = postcss.parse(selector).first;
+    try {
+        parse(rule);
+    } catch (e) {
+        t.snapshot(e.toString());
+    }
+}
+
+test('missing open square bracket', showCode, 'a b c] {}');
+test('missing open parenthesis', showCode, 'a b c) {}');
+test('missing pseudo class or pseudo element', showCode, 'a b c: {}');
+
+test('space in between colon and word (incorrect pseudo)', showCode, 'a b: c {}');
+test('string after colon (incorrect pseudo)', showCode, 'a b:"wow" {}');

src/__tests__/postcss.js

@@ -43,12 +43,14 @@ export default class Parser {
 
         const selector = new Selector();
         this.root.append(selector);
-
         this.current = selector;
+
+        this.css = typeof input.css === 'string' ? input.css : input.css.selector;
+
         if (this.lossy) {
-            this.tokens = tokenize({safe: input.safe, css: input.css.trim()});
+            this.tokens = tokenize({safe: input.safe, css: this.css.trim()});
         } else {
-            this.tokens = tokenize(input);
+            this.tokens = tokenize(Object.assign({}, input, {css: this.css}));
         }
 
         return this.loop();
@@ -175,20 +177,26 @@ export default class Parser {
         this.position ++;
     }
 
-    error (message) {
-        throw new this.input.error(message); // eslint-disable-line new-cap
+    error (message, opts) {
+        throw new this.input.error(message, opts); // eslint-disable-line new-cap
     }
 
     missingBackslash () {
-        return this.error('Expected a backslash preceding the semicolon.');
+        return this.error('Expected a backslash preceding the semicolon.', {
+            index: this.currToken[6],
+        });
     }
 
     missingParenthesis () {
-        return this.error('Expected opening parenthesis.');
+        return this.error('Expected an opening parenthesis.', {
+            index: this.currToken[6],
+        });
     }
 
     missingSquareBracket () {
-        return this.error('Expected opening square bracket.');
+        return this.error('Expected an opening square bracket.', {
+            index: this.currToken[6],
+        });
     }
 
     namespace () {
@@ -256,7 +264,9 @@ export default class Parser {
             }
         }
         if (balanced) {
-            this.error('Expected closing parenthesis.');
+            this.error('Expected a closing parenthesis.', {
+                index: this.currToken[6],
+            });
         }
     }
 
@@ -268,7 +278,9 @@ export default class Parser {
             this.position ++;
         }
         if (!this.currToken) {
-            return this.error('Expected pseudo-class or pseudo-element');
+            return this.error('Expected a pseudo-class or pseudo-element.', {
+                index: this.position - 1,
+            });
         }
         if (this.currToken[0] === tokens.word) {
             this.splitWord(false, (first, length) => {
@@ -288,11 +300,15 @@ export default class Parser {
                     this.nextToken &&
                     this.nextToken[0] === tokens.openParenthesis
                 ) {
-                    this.error('Misplaced parenthesis.');
+                    this.error('Misplaced parenthesis.', {
+                        index: this.nextToken[6],
+                    });
                 }
             });
         } else {
-            this.error('Unexpected "' + this.currToken[0] + '" found.');
+            this.error('Expected a pseudo-class or pseudo-element.', {
+                index: this.currToken[6],
+            });
         }
     }