first commit

node_modules/postcss-discard-overridden/src/__tests__/fixtures/counter-style.css

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+@counter-style my-alpha {
+  system: fixed;
+  symbols: A B C;
+  suffix: " ";
+}
+
+@COUNTER-STYLE my-alpha {
+    system: fixed;
+    symbols: A B C;
+    suffix: " ";
+}
+
+@counter-style my-alpha {
+  system: fixed;
+  symbols: Ⓐ Ⓑ Ⓒ;
+  suffix: " ";
+}
+
+@media (max-width: 400px) {
+  @counter-style my-alpha {
+    system: fixed;
+    symbols: A B C;
+    suffix: " ";
+  }
+
+  @supports (display: flex) {
+    @counter-style my-alpha {
+      system: fixed;
+      symbols: a b c;
+      suffix: " ";
+    }
+  }
+
+  @counter-style my-alpha {
+    system: fixed;
+    symbols: Ⓐ Ⓑ Ⓒ;
+    suffix: " ";
+  }
+}

node_modules/postcss-discard-overridden/src/__tests__/fixtures/counter-style.post.css

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+@counter-style my-alpha {
+  system: fixed;
+  symbols: Ⓐ Ⓑ Ⓒ;
+  suffix: " ";
+}
+
+@media (max-width: 400px) {
+
+  @supports (display: flex) {
+    @counter-style my-alpha {
+      system: fixed;
+      symbols: a b c;
+      suffix: " ";
+    }
+  }
+
+  @counter-style my-alpha {
+    system: fixed;
+    symbols: Ⓐ Ⓑ Ⓒ;
+    suffix: " ";
+  }
+}

node_modules/postcss-discard-overridden/src/__tests__/fixtures/keyframes.css

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+@-webkit-keyframes fade-in {
+  0% {
+    opacity: 0;
+  }
+  100% {
+    opacity: 0.8;
+  }
+}
+@-WEBKIT-KEYFRAMES fade-in {
+    0% {
+        opacity: 0;
+    }
+    100% {
+        opacity: 0.8;
+    }
+}
+@keyframes fade-in {
+  0% {
+    opacity: 0;
+  }
+  100% {
+    opacity: 0.8;
+  }
+}
+@KEYFRAMES fade-in {
+    0% {
+        opacity: 0;
+    }
+    100% {
+        opacity: 0.8;
+    }
+}
+@media (max-width: 500px) {
+  @-webkit-keyframes fade-in {
+    0% {
+      opacity: 0;
+    }
+    100% {
+      opacity: 1;
+    }
+  }
+  @keyframes fade-in {
+    0% {
+      opacity: 0;
+    }
+    100% {
+      opacity: 1;
+    }
+  }
+  @-webkit-keyframes fade-in {
+    0% {
+      opacity: 0;
+    }
+    100% {
+      opacity: 0.8;
+    }
+  }
+  @keyframes fade-in {
+    0% {
+      opacity: 0;
+    }
+    100% {
+      opacity: 0.8;
+    }
+  }
+  @supports (display: flex) {
+    @-webkit-keyframes fade-in {
+      0% {
+        opacity: 0;
+      }
+      100% {
+        opacity: 1;
+      }
+    }
+    @keyframes fade-in {
+      0% {
+        opacity: 0;
+      }
+      100% {
+        opacity: 1;
+      }
+    }
+  }
+}
+@-webkit-keyframes fade-in {
+  0% {
+    opacity: 0;
+  }
+  100% {
+    opacity: 1;
+  }
+}
+@keyframes fade-in {
+  0% {
+    opacity: 0;
+  }
+  100% {
+    opacity: 1;
+  }
+}

node_modules/postcss-discard-overridden/src/__tests__/fixtures/keyframes.post.css

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+@media (max-width: 500px) {
+  @-webkit-keyframes fade-in {
+    0% {
+      opacity: 0;
+    }
+    100% {
+      opacity: 0.8;
+    }
+  }
+  @keyframes fade-in {
+    0% {
+      opacity: 0;
+    }
+    100% {
+      opacity: 0.8;
+    }
+  }
+  @supports (display: flex) {
+    @-webkit-keyframes fade-in {
+      0% {
+        opacity: 0;
+      }
+      100% {
+        opacity: 1;
+      }
+    }
+    @keyframes fade-in {
+      0% {
+        opacity: 0;
+      }
+      100% {
+        opacity: 1;
+      }
+    }
+  }
+}
+@-webkit-keyframes fade-in {
+  0% {
+    opacity: 0;
+  }
+  100% {
+    opacity: 1;
+  }
+}
+@keyframes fade-in {
+  0% {
+    opacity: 0;
+  }
+  100% {
+    opacity: 1;
+  }
+}

node_modules/postcss-discard-overridden/src/__tests__/index.js

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+import fs from 'fs';
+import postcss from 'postcss';
+import test from 'ava';
+import {diffLines} from 'diff';
+import chalk from 'chalk';
+import plugin from '../';
+
+function getDiff (left, right) {
+    let msg = ['\n'];
+    diffLines(left, right).forEach(item => {
+        if (item.added || item.removed) {
+            let text = item.value
+                .replace('\n', '\u00b6\n')
+                .replace('\ufeff', '[[BOM]]');
+            msg.push(chalk[item.added ? 'green' : 'red'](text));
+        } else {
+            let value = item.value.replace('\ufeff', '[[BOM]]');
+            let lines = value.split('\n');
+
+            // max line count for each item
+            let keepLines = 6;
+            // lines to be omitted
+            let omitLines = lines.length - keepLines;
+            if (lines.length > keepLines) {
+                lines.splice(
+                    Math.floor(keepLines / 2),
+                    omitLines,
+                    chalk.gray('(...' + omitLines + ' lines omitted...)')
+                );
+            }
+            msg.concat(lines);
+        }
+    });
+    msg.push('\n');
+    return msg.map(line => '  ' + line).join('');
+}
+
+function read (file) {
+    return fs.readFileSync(__dirname + `/fixtures/${file}.css`, {encoding: 'utf-8'});
+}
+
+function exec (t, input) {
+    let output = read(`${input}.post`);
+    return postcss([ plugin() ]).process(read(input))
+        .then( result => {
+            if (result.css !== output) {
+                t.fail(getDiff(result.css, output));
+            }
+            t.deepEqual(result.warnings().length, 0);
+        });
+}
+
+test(
+    'Overridden @keyframes should be discarded correctly.',
+    exec,
+    'keyframes'
+);
+
+test(
+    'Overridden @counter-style should be discarded correctly.',
+    exec,
+    'counter-style'
+);

node_modules/postcss-discard-overridden/src/index.js

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+import postcss from 'postcss';
+
+const OVERRIDABLE_RULES = ['keyframes', 'counter-style'];
+const SCOPE_RULES = ['media', 'supports'];
+
+function isOverridable (name) {
+    return ~OVERRIDABLE_RULES.indexOf(postcss.vendor.unprefixed(name.toLowerCase()));
+}
+
+function isScope (name) {
+    return ~SCOPE_RULES.indexOf(postcss.vendor.unprefixed(name.toLowerCase()));
+}
+
+function getScope (node) {
+    let current = node.parent;
+    const chain = [node.name.toLowerCase(), node.params];
+    do {
+        if (current.type === 'atrule' && isScope(current.name)) {
+            chain.unshift(current.name + ' ' + current.params);
+        }
+        current = current.parent;
+    } while (current);
+    return chain.join('|');
+}
+
+export default postcss.plugin('postcss-discard-overridden', () => {
+    return css => {
+        const cache = {};
+        const rules = [];
+        css.walkAtRules(node => {
+            if (isOverridable(node.name)) {
+                const scope = getScope(node);
+                cache[scope] = node;
+                rules.push({
+                    node,
+                    scope,
+                });
+            }
+        });
+        rules.forEach(rule => {
+            if (cache[rule.scope] !== rule.node) {
+                rule.node.remove();
+            }
+        });
+    };
+});