Split template module into multiple files.

packages/babel-template/src/string.js

@@ -0,0 +1,122 @@
+import cloneDeep from "lodash/cloneDeep";
+import has from "lodash/has";
+import traverse from "@babel/traverse";
+import * as babylon from "babylon";
+import { codeFrameColumns } from "@babel/code-frame";
+
+const FROM_TEMPLATE = new Set();
+
+export default function factory(code: string, opts?: Object): Function {
+  // since we lazy parse the template, we get the current stack so we have the
+  // original stack to append if it errors when parsing
+  let stack;
+  try {
+    // error stack gets populated in IE only on throw
+    // (https://msdn.microsoft.com/en-us/library/hh699850(v=vs.94).aspx)
+    throw new Error();
+  } catch (error) {
+    if (error.stack) {
+      // error.stack does not exists in IE <= 9
+      stack = error.stack
+        .split("\n")
+        .slice(2)
+        .join("\n");
+    }
+  }
+
+  opts = Object.assign(
+    {
+      allowReturnOutsideFunction: true,
+      allowSuperOutsideMethod: true,
+      preserveComments: false,
+      sourceType: "module",
+    },
+    opts,
+  );
+
+  let getAst = function() {
+    let ast;
+
+    try {
+      ast = babylon.parse(code, opts);
+
+      ast = traverse.removeProperties(ast, {
+        preserveComments: opts.preserveComments,
+      });
+    } catch (err) {
+      const loc = err.loc;
+      if (loc) {
+        err.loc = null;
+        err.message += "\n" + codeFrameColumns(code, { start: loc });
+      }
+      err.stack = `${err.stack}\n    ==========================\n${stack}`;
+      throw err;
+    }
+
+    getAst = function() {
+      return ast;
+    };
+
+    return ast;
+  };
+
+  return function(...args) {
+    return useTemplate(getAst(), args);
+  };
+}
+
+function useTemplate(ast, nodes?: Array<Object>) {
+  ast = cloneDeep(ast);
+  const { program } = ast;
+
+  if (nodes.length) {
+    traverse.cheap(ast, function(node) {
+      FROM_TEMPLATE.add(node);
+    });
+
+    traverse(ast, templateVisitor, null, nodes);
+
+    FROM_TEMPLATE.clear();
+  }
+
+  if (program.body.length > 1) {
+    return program.body;
+  } else {
+    return program.body[0];
+  }
+}
+
+const templateVisitor = {
+  // 360
+  noScope: true,
+
+  Identifier(path, args) {
+    const { node, parentPath } = path;
+    if (!FROM_TEMPLATE.has(node)) return path.skip();
+
+    let replacement;
+    if (has(args[0], node.name)) {
+      replacement = args[0][node.name];
+    } else if (node.name[0] === "$") {
+      const i = +node.name.slice(1);
+      if (args[i]) replacement = args[i];
+    }
+
+    if (parentPath.isExpressionStatement()) {
+      path = parentPath;
+    }
+
+    if (replacement === null) {
+      path.remove();
+    } else if (replacement) {
+      path.replaceInline(replacement);
+      path.skip();
+    }
+  },
+
+  exit({ node }) {
+    if (!node.loc) {
+      traverse.clearNode(node);
+    }
+  },
+};