feat: initial commit

node_modules/@babel/helpers/scripts/build-helper-metadata.js

@@ -0,0 +1,209 @@
+// NOTE: This file must be compatible with old Node.js versions, since it runs
+// during testing.
+
+/**
+ * @typedef {Object} HelperMetadata
+ * @property {string[]} globals
+ * @property {{ [name: string]: string[] }} locals
+ * @property {{ [name: string]: string[] }} dependencies
+ * @property {string[]} exportBindingAssignments
+ * @property {string} exportName
+ */
+
+/**
+ * Given a file AST for a given helper, get a bunch of metadata about it so that Babel can quickly render
+ * the helper is whatever context it is needed in.
+ *
+ * @param {typeof import("@babel/core")} babel
+ *
+ * @returns {HelperMetadata}
+ */
+export function getHelperMetadata(babel, code, helperName) {
+  const globals = new Set();
+  // Maps imported identifier name -> helper name
+  const dependenciesBindings = new Map();
+
+  let exportName;
+  const exportBindingAssignments = [];
+  // helper name -> reference paths
+  const dependencies = new Map();
+  // local variable name -> reference paths
+  const locals = new Map();
+
+  const spansToRemove = [];
+
+  const validateDefaultExport = decl => {
+    if (exportName) {
+      throw new Error(
+        `Helpers can have only one default export (in ${helperName})`
+      );
+    }
+
+    if (!decl.isFunctionDeclaration() || !decl.node.id) {
+      throw new Error(
+        `Helpers can only export named function declarations (in ${helperName})`
+      );
+    }
+  };
+
+  /** @type {import("@babel/traverse").Visitor} */
+  const dependencyVisitor = {
+    Program(path) {
+      for (const child of path.get("body")) {
+        if (child.isImportDeclaration()) {
+          if (
+            child.get("specifiers").length !== 1 ||
+            !child.get("specifiers.0").isImportDefaultSpecifier()
+          ) {
+            throw new Error(
+              `Helpers can only import a default value (in ${helperName})`
+            );
+          }
+          dependenciesBindings.set(
+            child.node.specifiers[0].local.name,
+            child.node.source.value
+          );
+          dependencies.set(child.node.source.value, []);
+          spansToRemove.push([child.node.start, child.node.end]);
+          child.remove();
+        }
+      }
+      for (const child of path.get("body")) {
+        if (child.isExportDefaultDeclaration()) {
+          const decl = child.get("declaration");
+          validateDefaultExport(decl);
+
+          exportName = decl.node.id.name;
+          spansToRemove.push([child.node.start, decl.node.start]);
+          child.replaceWith(decl.node);
+        } else if (
+          child.isExportNamedDeclaration() &&
+          child.node.specifiers.length === 1 &&
+          child.get("specifiers.0.exported").isIdentifier({ name: "default" })
+        ) {
+          const { name } = child.node.specifiers[0].local;
+
+          validateDefaultExport(child.scope.getBinding(name).path);
+
+          exportName = name;
+          spansToRemove.push([child.node.start, child.node.end]);
+          child.remove();
+        } else if (
+          process.env.IS_BABEL_OLD_E2E &&
+          child.isExportNamedDeclaration() &&
+          child.node.specifiers.length === 0
+        ) {
+          spansToRemove.push([child.node.start, child.node.end]);
+          child.remove();
+        } else if (
+          child.isExportAllDeclaration() ||
+          child.isExportNamedDeclaration()
+        ) {
+          throw new Error(`Helpers can only export default (in ${helperName})`);
+        }
+      }
+
+      path.scope.crawl();
+
+      const bindings = path.scope.getAllBindings();
+      Object.keys(bindings).forEach(name => {
+        if (dependencies.has(name)) return;
+
+        const binding = bindings[name];
+
+        const references = [
+          ...binding.path.getBindingIdentifierPaths(true)[name].map(makePath),
+          ...binding.referencePaths.map(makePath),
+        ];
+        for (const violation of binding.constantViolations) {
+          violation.getBindingIdentifierPaths(true)[name].forEach(path => {
+            references.push(makePath(path));
+          });
+        }
+
+        locals.set(name, references);
+      });
+    },
+    ReferencedIdentifier(child) {
+      const name = child.node.name;
+      const binding = child.scope.getBinding(name);
+      if (!binding) {
+        if (dependenciesBindings.has(name)) {
+          dependencies
+            .get(dependenciesBindings.get(name))
+            .push(makePath(child));
+        } else if (name !== "arguments" || child.scope.path.isProgram()) {
+          globals.add(name);
+        }
+      }
+    },
+    AssignmentExpression(child) {
+      const left = child.get("left");
+
+      if (!(exportName in left.getBindingIdentifiers())) return;
+
+      if (!left.isIdentifier()) {
+        throw new Error(
+          `Only simple assignments to exports are allowed in helpers (in ${helperName})`
+        );
+      }
+
+      const binding = child.scope.getBinding(exportName);
+
+      if (binding && binding.scope.path.isProgram()) {
+        exportBindingAssignments.push(makePath(child));
+      }
+    },
+  };
+
+  babel.transformSync(code, {
+    configFile: false,
+    babelrc: false,
+    plugins: [() => ({ visitor: dependencyVisitor })],
+  });
+
+  if (!exportName) throw new Error("Helpers must have a named default export.");
+
+  // Process these in reverse so that mutating the references does not invalidate any later paths in
+  // the list.
+  exportBindingAssignments.reverse();
+
+  spansToRemove.sort(([start1], [start2]) => start2 - start1);
+  for (const [start, end] of spansToRemove) {
+    code = code.slice(0, start) + code.slice(end);
+  }
+
+  return [
+    code,
+    {
+      globals: Array.from(globals),
+      locals: Object.fromEntries(locals),
+      dependencies: Object.fromEntries(dependencies),
+      exportBindingAssignments,
+      exportName,
+    },
+  ];
+}
+
+function makePath(path) {
+  const parts = [];
+
+  for (; path.parentPath; path = path.parentPath) {
+    parts.push(path.key);
+    if (path.inList) parts.push(path.listKey);
+  }
+
+  return parts.reverse().join(".");
+}
+
+export function stringifyMetadata(metadata) {
+  return `\
+    {
+      globals: ${JSON.stringify(metadata.globals)},
+      locals: ${JSON.stringify(metadata.locals)},
+      exportBindingAssignments: ${JSON.stringify(metadata.exportBindingAssignments)},
+      exportName: ${JSON.stringify(metadata.exportName)},
+      dependencies: ${JSON.stringify(metadata.dependencies)},
+    }
+  `;
+}