add some packages

node_modules/babel-plugin-minify-simplify/lib/if-statement.js

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+"use strict";
+
+const REPLACED = Symbol("replaced");
+
+const h = require("./helpers");
+
+module.exports = t => {
+  function mergeNestedIfs(path) {
+    const consequent = path.get("consequent");
+    const alternate = path.get("alternate"); // not nested if
+
+    if (!consequent.isIfStatement()) return; // there are no alternate nodes in both the if statements (nested)
+
+    if (alternate.node || consequent.get("alternate").node) return;
+    const test = path.get("test");
+    test.replaceWith(t.logicalExpression("&&", test.node, consequent.get("test").node));
+    consequent.replaceWith(t.clone(consequent.get("consequent").node));
+  } // No alternate, make into a guarded expression
+
+
+  function toGuardedExpression(path) {
+    const node = path.node;
+
+    if (node.consequent && !node.alternate && node.consequent.type === "ExpressionStatement") {
+      let op = "&&";
+
+      if (t.isUnaryExpression(node.test, {
+        operator: "!"
+      })) {
+        node.test = node.test.argument;
+        op = "||";
+      }
+
+      path.replaceWith(t.expressionStatement(t.logicalExpression(op, node.test, node.consequent.expression)));
+      return REPLACED;
+    }
+  } // both consequent and alternate are expressions, turn into ternary
+
+
+  function toTernary(path) {
+    const node = path.node;
+
+    if (t.isExpressionStatement(node.consequent) && t.isExpressionStatement(node.alternate)) {
+      path.replaceWith(t.conditionalExpression(node.test, node.consequent.expression, node.alternate.expression));
+      return REPLACED;
+    }
+  } // consequent and alternate are return -- conditional.
+
+
+  function toConditional(path) {
+    const node = path.node;
+
+    if (t.isReturnStatement(node.consequent) && t.isReturnStatement(node.alternate)) {
+      if (!node.consequent.argument && !node.alternate.argument) {
+        path.replaceWith(t.expressionStatement(node.test));
+        return REPLACED;
+      }
+
+      path.replaceWith(t.returnStatement(t.conditionalExpression(node.test, node.consequent.argument || h.VOID_0(t), node.alternate.argument || h.VOID_0(t))));
+      return REPLACED;
+    }
+  } // There is nothing after this If block. And one or both
+  // of the consequent and alternate are either expression statment
+  // or return statements.
+
+
+  function toReturn(path) {
+    const node = path.node;
+
+    if (!path.getSibling(path.key + 1).node && path.parentPath && path.parentPath.parentPath && path.parentPath.parentPath.isFunction()) {
+      // Only the consequent is a return, void the alternate.
+      if (t.isReturnStatement(node.consequent) && t.isExpressionStatement(node.alternate)) {
+        if (!node.consequent.argument) {
+          path.replaceWith(t.expressionStatement(t.logicalExpression("||", node.test, node.alternate.expression)));
+          return REPLACED;
+        }
+
+        path.replaceWith(t.returnStatement(t.conditionalExpression(node.test, node.consequent.argument || h.VOID_0(t), t.unaryExpression("void", node.alternate.expression, true))));
+        return REPLACED;
+      } // Only the alternate is a return, void the consequent.
+
+
+      if (t.isReturnStatement(node.alternate) && t.isExpressionStatement(node.consequent)) {
+        if (!node.alternate.argument) {
+          path.replaceWith(t.expressionStatement(t.logicalExpression("&&", node.test, node.consequent.expression)));
+          return REPLACED;
+        }
+
+        path.replaceWith(t.returnStatement(t.conditionalExpression(node.test, t.unaryExpression("void", node.consequent.expression, true), node.alternate.argument || h.VOID_0(t))));
+        return REPLACED;
+      }
+
+      if (t.isReturnStatement(node.consequent) && !node.alternate) {
+        if (!node.consequent.argument) {
+          path.replaceWith(t.expressionStatement(node.test));
+          return REPLACED;
+        } // This would only be worth it if the previous statement was an if
+        // because then we may merge to create a conditional.
+
+
+        if (path.getSibling(path.key - 1).isIfStatement()) {
+          path.replaceWith(t.returnStatement(t.conditionalExpression(node.test, node.consequent.argument || h.VOID_0(t), h.VOID_0(t))));
+          return REPLACED;
+        }
+      }
+
+      if (t.isReturnStatement(node.alternate) && !node.consequent) {
+        if (!node.alternate.argument) {
+          path.replaceWith(t.expressionStatement(node.test));
+          return REPLACED;
+        } // Same as above.
+
+
+        if (path.getSibling(path.key - 1).isIfStatement()) {
+          path.replaceWith(t.returnStatement(t.conditionalExpression(node.test, node.alternate.argument || h.VOID_0(t), h.VOID_0(t))));
+          return REPLACED;
+        }
+      }
+    }
+
+    let next = path.getSibling(path.key + 1); // If the next satatement(s) is an if statement and we can simplify that
+    // to potentailly be an expression (or a return) then this will make it
+    // easier merge.
+
+    if (next.isIfStatement()) {
+      next.pushContext(path.context);
+      next.visit();
+      next.popContext();
+      next = path.getSibling(path.key + 1);
+    } // Some other visitor might have deleted our node. OUR NODE ;_;
+
+
+    if (!path.node) {
+      return;
+    } // No alternate but the next statement is a return
+    // also turn into a return conditional
+
+
+    if (t.isReturnStatement(node.consequent) && !node.alternate && next.isReturnStatement()) {
+      const nextArg = next.node.argument || h.VOID_0(t);
+      next.remove();
+      path.replaceWith(t.returnStatement(t.conditionalExpression(node.test, node.consequent.argument || h.VOID_0(t), nextArg)));
+      return REPLACED;
+    } // Next is the last expression, turn into a return while void'ing the exprs
+
+
+    if (path.parentPath && path.parentPath.parentPath && path.parentPath.parentPath.isFunction() && !path.getSibling(path.key + 2).node && t.isReturnStatement(node.consequent) && !node.alternate && next.isExpressionStatement()) {
+      const nextExpr = next.node.expression;
+      next.remove();
+
+      if (node.consequent.argument) {
+        path.replaceWith(t.returnStatement(t.conditionalExpression(node.test, node.consequent.argument, t.unaryExpression("void", nextExpr, true))));
+        return REPLACED;
+      }
+
+      path.replaceWith(t.logicalExpression("||", node.test, nextExpr));
+      return REPLACED;
+    }
+  } // Remove else for if-return
+
+
+  function removeUnnecessaryElse(path) {
+    const node = path.node;
+    const consequent = path.get("consequent");
+    const alternate = path.get("alternate");
+
+    if (consequent.node && alternate.node && (consequent.isReturnStatement() || consequent.isBlockStatement() && t.isReturnStatement(consequent.node.body[consequent.node.body.length - 1])) && ( // don't hoist declarations
+    // TODO: validate declarations after fixing scope issues
+    alternate.isBlockStatement() ? !alternate.get("body").some(stmt => stmt.isVariableDeclaration({
+      kind: "let"
+    }) || stmt.isVariableDeclaration({
+      kind: "const"
+    })) : true)) {
+      path.insertAfter(alternate.isBlockStatement() ? alternate.node.body.map(el => t.clone(el)) : t.clone(alternate.node));
+      node.alternate = null;
+      return REPLACED;
+    }
+  }
+
+  function runTransforms(path) {
+    // ordered
+    const transforms = [toGuardedExpression, toTernary, toConditional, toReturn, removeUnnecessaryElse]; // run each of the replacement till we replace something
+    // which is identified by the Symbol(REPLACED) that each of the
+    // functions return when they replace something
+
+    for (var _i = 0; _i < transforms.length; _i++) {
+      const transform = transforms[_i];
+
+      if (transform(path) === REPLACED) {
+        break;
+      }
+    }
+  } // If the consequent is if and the altenrate is not then
+  // switch them out. That way we know we don't have to print
+  // a block.x
+
+
+  function switchConsequent(path) {
+    const node = path.node;
+
+    if (!node.alternate) {
+      return;
+    }
+
+    if (!t.isIfStatement(node.consequent)) {
+      return;
+    }
+
+    if (t.isIfStatement(node.alternate)) {
+      return;
+    }
+
+    node.test = t.unaryExpression("!", node.test, true);
+    var _ref = [node.consequent, node.alternate];
+    node.alternate = _ref[0];
+    node.consequent = _ref[1];
+  } // Make if statements with conditional returns in the body into
+  // an if statement that guards the rest of the block.
+
+
+  function conditionalReturnToGuards(path) {
+    const node = path.node;
+
+    if (!path.inList || !path.get("consequent").isBlockStatement() || node.alternate) {
+      return;
+    }
+
+    let ret;
+    let test;
+    const exprs = [];
+    const statements = node.consequent.body;
+
+    for (let i = 0, statement; statement = statements[i]; i++) {
+      if (t.isExpressionStatement(statement)) {
+        exprs.push(statement.expression);
+      } else if (t.isIfStatement(statement)) {
+        if (i < statements.length - 1) {
+          // This isn't the last statement. Bail.
+          return;
+        }
+
+        if (statement.alternate) {
+          return;
+        }
+
+        if (!t.isReturnStatement(statement.consequent)) {
+          return;
+        }
+
+        ret = statement.consequent;
+        test = statement.test;
+      } else {
+        return;
+      }
+    }
+
+    if (!test || !ret) {
+      return;
+    }
+
+    exprs.push(test);
+    const expr = exprs.length === 1 ? exprs[0] : t.sequenceExpression(exprs);
+    const replacement = t.logicalExpression("&&", node.test, expr);
+    path.replaceWith(t.ifStatement(replacement, ret, null));
+  }
+
+  return {
+    mergeNestedIfs,
+    simplify: runTransforms,
+    switchConsequent,
+    conditionalReturnToGuards
+  };
+};