flow like the river

VISUALIZACION/node_modules/postcss-zindex/index.js

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+'use strict';
+
+var postcss = require('postcss');
+
+module.exports = postcss.plugin('postcss-zindex', function (opts) {
+    opts = opts || {};
+    return function (css) {
+        var cache = require('./lib/layerCache')(opts);
+        var nodes = [];
+        var abort = false;
+        // First pass; cache all z indexes
+        css.walkDecls('z-index', function (decl) {
+            // Check that no negative values exist. Rebasing is only
+            // safe if all indices are positive numbers.
+            if (decl.value[0] === '-') {
+                abort = true;
+                // Stop PostCSS iterating through the rest of the decls
+                return false;
+            }
+            nodes.push(decl);
+            cache.addValue(decl.value);
+        });
+
+        // Abort if we found any negative values
+        // or there are no z-index declarations
+        if (abort || !nodes.length) {
+            return;
+        }
+
+        cache.optimizeValues();
+
+        // Second pass; optimize
+        nodes.forEach(function (decl) {
+            // Need to coerce to string so that the
+            // AST is updated correctly
+            decl.value = cache.getValue(decl.value).toString();
+        });
+    };
+});