add some packages

node_modules/babel-plugin-minify-constant-folding/lib/index.js

@@ -0,0 +1,230 @@
+"use strict";
+
+const evaluate = require("babel-helper-evaluate-path");
+
+const _require = require("./replacements"),
+      FALLBACK_HANDLER = _require.FALLBACK_HANDLER;
+
+function getName(member) {
+  if (member.computed) {
+    switch (member.property.type) {
+      case "StringLiteral":
+      case "NumericLiteral":
+        return member.property.value;
+
+      case "TemplateLiteral":
+        return;
+    }
+  } else {
+    return member.property.name;
+  }
+}
+
+function swap(path, member, handlers, ...args) {
+  const key = getName(member.node);
+  if (key === void 0) return false;
+  let handler;
+
+  if (hop(handlers, key) && typeof handlers[key] === "function") {
+    handler = handlers[key];
+  } else if (typeof handlers[FALLBACK_HANDLER] === "function") {
+    handler = handlers[FALLBACK_HANDLER].bind(member.get("object"), key);
+  } else {
+    return false;
+  }
+
+  const replacement = handler.apply(member.get("object"), args);
+
+  if (replacement) {
+    path.replaceWith(replacement);
+    return true;
+  }
+
+  return false;
+}
+
+module.exports = babel => {
+  const replacements = require("./replacements.js")(babel);
+
+  const seen = Symbol("seen");
+  const t = babel.types;
+  return {
+    name: "minify-constant-folding",
+    visitor: {
+      // Evaluate string expressions that are next to each other
+      // but are not actually a binary expression.
+      // "a" + b + "c" + "d" -> "a" + b + "cd"
+      BinaryExpression(path) {
+        if (!path.isBinaryExpression({
+          operator: "+"
+        })) {
+          return;
+        }
+
+        let literal, bin;
+        const left = path.get("left");
+        const right = path.get("right");
+
+        if (right.isStringLiteral()) {
+          literal = right;
+
+          if (left.isBinaryExpression({
+            operator: "+"
+          })) {
+            bin = left;
+          } else {
+            return;
+          }
+        } else if (left.isStringLiteral()) {
+          literal = left;
+
+          if (right.isBinaryExpression({
+            operator: "+"
+          })) {
+            bin = right;
+          } else {
+            return;
+          }
+        } else {
+          return;
+        }
+
+        const relevant = getLeaf(bin, literal.key);
+
+        if (!relevant) {
+          return;
+        }
+
+        const value = literal.key === "right" ? relevant.node.value + literal.node.value : literal.node.value + relevant.node.value;
+        relevant.replaceWith(t.stringLiteral(value));
+        path.replaceWith(bin.node);
+
+        function getLeaf(path, direction) {
+          if (path.isStringLiteral()) {
+            return path;
+          } else if (path.isBinaryExpression({
+            operator: "+"
+          })) {
+            return getLeaf(path.get(direction), direction);
+          }
+        }
+      },
+
+      // TODO: look into evaluating binding too (could result in more code, but gzip?)
+      Expression(path, {
+        opts: {
+          tdz = false
+        } = {}
+      }) {
+        const node = path.node,
+              parent = path.parent;
+
+        if (node[seen]) {
+          return;
+        }
+
+        if (path.isLiteral()) {
+          return;
+        }
+
+        if (!path.isPure()) {
+          return;
+        } // Avoid replacing the values for identifiers in exports
+
+
+        if (t.isExportSpecifier(parent)) {
+          return;
+        } // -0 maybe compared via dividing and then checking against -Infinity
+        // Also -X will always be -X.
+
+
+        if (t.isUnaryExpression(node, {
+          operator: "-"
+        }) && t.isNumericLiteral(node.argument)) {
+          return;
+        } // We have a transform that converts true/false to !0/!1
+
+
+        if (t.isUnaryExpression(node, {
+          operator: "!"
+        }) && t.isNumericLiteral(node.argument)) {
+          if (node.argument.value === 0 || node.argument.value === 1) {
+            return;
+          }
+        } // void 0 is used for undefined.
+
+
+        if (t.isUnaryExpression(node, {
+          operator: "void"
+        }) && t.isNumericLiteral(node.argument, {
+          value: 0
+        })) {
+          return;
+        }
+
+        const res = evaluate(path, {
+          tdz
+        });
+
+        if (res.confident) {
+          // Avoid fractions because they can be longer than the original expression.
+          // There is also issues with number precision?
+          if (typeof res.value === "number" && !Number.isInteger(res.value)) {
+            return;
+          } // Preserve -0
+
+
+          if (typeof res.value === "number" && res.value === 0) {
+            if (1 / res.value === -Infinity) {
+              const node = t.unaryExpression("-", t.numericLiteral(0), true);
+              node[seen] = true;
+              path.replaceWith(node);
+              return;
+            }
+          } // this will convert object to object but
+          // t.valueToNode has other effects where property name
+          // is not treated for the respective environment.
+          // So we bail here for objects and let other plugins
+          // take care of converting String literal to Identifier
+
+
+          if (typeof res.value === "object") {
+            return;
+          }
+
+          const node = t.valueToNode(res.value);
+          node[seen] = true;
+          path.replaceWith(node);
+        }
+      },
+
+      CallExpression(path) {
+        const node = path.node;
+        const member = path.get("callee");
+
+        if (t.isMemberExpression(member)) {
+          const helpers = replacements[member.node.object.type];
+          if (!helpers || !helpers.calls) return; // find if the input can be constant folded
+
+          if (typeof helpers.canReplace === "function" && !helpers.canReplace.call(member.get("object"))) {
+            return;
+          }
+
+          swap(path, member, helpers.calls, ...node.arguments);
+        }
+      },
+
+      MemberExpression(path) {
+        const node = path.node;
+        const helpers = replacements[node.object.type];
+        if (!helpers || !helpers.members) return;
+        swap(path, path, helpers.members);
+      }
+
+    }
+  };
+};
+
+function hop(o, key) {
+  return Object.prototype.hasOwnProperty.call(o, key);
+}