index.js

import * as t from "@babel/types";
import { addNamed, addNamespace, isModule } from "@babel/helper-module-imports";
import annotateAsPure from "@babel/helper-annotate-as-pure";

const DEFAULT = {
  importSource: "react",
  runtime: "automatic",
  pragma: "React.createElement",
  pragmaFrag: "React.Fragment",
};

export function helper(babel, options) {
  const FILE_NAME_VAR = "_jsxFileName";

  const JSX_SOURCE_ANNOTATION_REGEX = /\*?\s*@jsxImportSource\s+([^\s]+)/;
  const JSX_RUNTIME_ANNOTATION_REGEX = /\*?\s*@jsxRuntime\s+([^\s]+)/;

  const JSX_ANNOTATION_REGEX = /\*?\s*@jsx\s+([^\s]+)/;
  const JSX_FRAG_ANNOTATION_REGEX = /\*?\s*@jsxFrag\s+([^\s]+)/;

  // This is the number of possible import names
  // development: jsxDEV, Fragment, createElement
  // production: jsx, jsxs, Fragment, createElement
  const IMPORT_NAME_SIZE = options.development ? 3 : 4;

  const {
    importSource: IMPORT_SOURCE_DEFAULT = DEFAULT.importSource,
    runtime: RUNTIME_DEFAULT = DEFAULT.runtime,
    pragma: PRAGMA_DEFAULT = DEFAULT.pragma,
    pragmaFrag: PRAGMA_FRAG_DEFAULT = DEFAULT.pragmaFrag,
  } = options;

  const injectMetaPropertiesVisitor = {
    JSXOpeningElement(path, state) {
      for (const attr of path.get("attributes")) {
        if (!attr.isJSXElement()) continue;

        const { name } = attr.node.name;
        if (name === "__source" || name === "__self") {
          throw path.buildCodeFrameError(
            `__source and __self should not be defined in props and are reserved for internal usage.`,
          );
        }
      }

      const source = t.jsxAttribute(
        t.jsxIdentifier("__source"),
        t.jsxExpressionContainer(makeSource(path, state)),
      );
      const self = t.jsxAttribute(
        t.jsxIdentifier("__self"),
        t.jsxExpressionContainer(t.thisExpression()),
      );

      path.pushContainer("attributes", [source, self]);
    },
  };

  return {
    JSXNamespacedName(path, state) {
      const throwIfNamespace =
        state.opts.throwIfNamespace === undefined
          ? true
          : !!state.opts.throwIfNamespace;
      if (throwIfNamespace) {
        throw path.buildCodeFrameError(
          `Namespace tags are not supported by default. React's JSX doesn't support namespace tags. \
You can set \`throwIfNamespace: false\` to bypass this warning.`,
        );
      }
    },

    JSXSpreadChild(path) {
      throw path.buildCodeFrameError(
        "Spread children are not supported in React.",
      );
    },

    JSXElement: {
      exit(path, file) {
        let callExpr;
        if (
          file.get("@babel/plugin-react-jsx/runtime") === "classic" ||
          shouldUseCreateElement(path)
        ) {
          callExpr = buildCreateElementCall(path, file);
        } else {
          callExpr = buildJSXElementCall(path, file);
        }

        path.replaceWith(t.inherits(callExpr, path.node));
      },
    },

    JSXFragment: {
      exit(path, file) {
        let callExpr;
        if (file.get("@babel/plugin-react-jsx/runtime") === "classic") {
          callExpr = buildCreateElementFragmentCall(path, file);
        } else {
          callExpr = buildJSXFragmentCall(path, file);
        }

        path.replaceWith(t.inherits(callExpr, path.node));
      },
    },

    JSXAttribute(path) {
      if (t.isJSXElement(path.node.value)) {
        path.node.value = t.jsxExpressionContainer(path.node.value);
      }
    },

    Program: {
      enter(path, state) {
        if (hasJSX(path)) {
          const { file } = state;
          let runtime = RUNTIME_DEFAULT;

          // For jsx mode
          let source = IMPORT_SOURCE_DEFAULT;
          let sourceSet = !!options.importSource;

          // For createElement mode
          let pragma = PRAGMA_DEFAULT;
          let pragmaFrag = PRAGMA_FRAG_DEFAULT;
          let pragmaSet = !!options.pragma;
          let pragmaFragSet = !!options.pragmaFrag;

          if (file.ast.comments) {
            for (const comment of (file.ast.comments: Array<Object>)) {
              const sourceMatches = JSX_SOURCE_ANNOTATION_REGEX.exec(
                comment.value,
              );
              if (sourceMatches) {
                source = sourceMatches[1];
                sourceSet = true;
              }

              const runtimeMatches = JSX_RUNTIME_ANNOTATION_REGEX.exec(
                comment.value,
              );
              if (runtimeMatches) {
                runtime = runtimeMatches[1];
              }

              const jsxMatches = JSX_ANNOTATION_REGEX.exec(comment.value);
              if (jsxMatches) {
                pragma = jsxMatches[1];
                pragmaSet = true;
              }
              const jsxFragMatches = JSX_FRAG_ANNOTATION_REGEX.exec(
                comment.value,
              );
              if (jsxFragMatches) {
                pragmaFrag = jsxFragMatches[1];
                pragmaFragSet = true;
              }
            }
          }

          state.set("@babel/plugin-react-jsx/runtime", runtime);
          if (runtime === "classic") {
            if (sourceSet) {
              throw path.buildCodeFrameError(
                `importSource cannot be set when runtime is classic.`,
              );
            }
            state.set(
              "@babel/plugin-react-jsx/createElementIdentifier",
              createIdentifierParser(pragma),
            );
            state.set(
              "@babel/plugin-react-jsx/jsxFragIdentifier",
              createIdentifierParser(pragmaFrag),
            );
            state.set("@babel/plugin-react-jsx/usedFragment", false);
            state.set(
              "@babel/plugin-react-jsx/pragmaSet",
              pragma !== DEFAULT.pragma,
            );
            state.set(
              "@babel/plugin-react-jsx/pragmaFragSet",
              pragmaFrag !== DEFAULT.pragmaFrag,
            );
          } else if (runtime === "automatic") {
            if (pragmaSet || pragmaFragSet) {
              throw path.buildCodeFrameError(
                `pragma and pragmaFrag cannot be set when runtime is automatic.`,
              );
            }

            const importName = addAutoImports(path, {
              ...state.opts,
              source,
            });

            state.set(
              "@babel/plugin-react-jsx/jsxIdentifier",
              createIdentifierParser(
                createIdentifierName(
                  path,
                  options.development ? "jsxDEV" : "jsx",
                  importName,
                ),
              ),
            );
            state.set(
              "@babel/plugin-react-jsx/jsxStaticIdentifier",
              createIdentifierParser(
                createIdentifierName(
                  path,
                  options.development ? "jsxDEV" : "jsxs",
                  importName,
                ),
              ),
            );

            state.set(
              "@babel/plugin-react-jsx/createElementIdentifier",
              createIdentifierParser(
                createIdentifierName(path, "createElement", importName),
              ),
            );

            state.set(
              "@babel/plugin-react-jsx/jsxFragIdentifier",
              createIdentifierParser(
                createIdentifierName(path, "Fragment", importName),
              ),
            );

            state.set(
              "@babel/plugin-react-jsx/importSourceSet",
              source !== DEFAULT.importSource,
            );
          } else {
            throw path.buildCodeFrameError(
              `Runtime must be either "classic" or "automatic".`,
            );
          }

          if (options.development) {
            path.traverse(injectMetaPropertiesVisitor, state);
          }
        }
      },

      exit(path, state) {
        if (
          state.get("@babel/plugin-react-jsx/runtime") === "classic" &&
          state.get("@babel/plugin-react-jsx/pragmaSet") &&
          state.get("@babel/plugin-react-jsx/usedFragment") &&
          !state.get("@babel/plugin-react-jsx/pragmaFragSet")
        ) {
          throw new Error(
            "transform-react-jsx: pragma has been set but " +
              "pragmaFrag has not been set",
          );
        }
      },
    },
  };

  // We want to use React.createElement, even in the case of
  // jsx, for <div {...props} key={key} /> to distinguish it
  // from <div key={key} {...props} />. This is an intermediary
  // step while we deprecate key spread from props. Afterwards,
  // we will stop using createElement in the transform.
  function shouldUseCreateElement(path) {
    const openingPath = path.get("openingElement");
    const attributes = openingPath.node.attributes;

    let seenPropsSpread = false;
    for (let i = 0; i < attributes.length; i++) {
      const attr = attributes[i];
      if (
        seenPropsSpread &&
        t.isJSXAttribute(attr) &&
        attr.name.name === "key"
      ) {
        return true;
      } else if (t.isJSXSpreadAttribute(attr)) {
        seenPropsSpread = true;
      }
    }
    return false;
  }

  function createIdentifierName(path, name, importName) {
    if (isModule(path)) {
      const identifierName = `${importName[name]}`;
      return identifierName;
    } else {
      return `${importName[name]}.${name}`;
    }
  }

  function getImportNames(parentPath) {
    const imports = new Set();

    parentPath.traverse({
      "JSXElement|JSXFragment"(path) {
        if (path.type === "JSXFragment") imports.add("Fragment");
        const openingPath = path.get("openingElement");
        const validChildren = openingPath.parent.children.filter(
          child =>
            !t.isJSXEmptyExpression(child) &&
            !(t.isJSXText(child) && child.value.trim() === ""),
        );

        let importName;
        if (path.type === "JSXElement" && shouldUseCreateElement(path)) {
          importName = "createElement";
        } else if (options.development) {
          importName = "jsxDEV";
        } else if (validChildren.length > 1) {
          importName = "jsxs";
        } else {
          importName = "jsx";
        }
        imports.add(importName);

        if (imports.size === IMPORT_NAME_SIZE) {
          path.stop();
        }
      },
    });
    return imports;
  }

  function hasJSX(parentPath) {
    let fileHasJSX = false;
    parentPath.traverse({
      "JSXElement|JSXFragment"(path) {
        fileHasJSX = true;
        path.stop();
      },
    });

    return fileHasJSX;
  }

  function getSource(source, importName) {
    switch (importName) {
      case "Fragment":
        return `${source}/${
          options.development ? "jsx-dev-runtime" : "jsx-runtime"
        }`;
      case "jsxDEV":
        return `${source}/jsx-dev-runtime`;
      case "jsx":
      case "jsxs":
        return `${source}/jsx-runtime`;
      case "createElement":
        return source;
    }
  }

  function addAutoImports(path, state) {
    const imports = getImportNames(path, state);
    if (isModule(path)) {
      // import {jsx} from "react";
      // import {createElement} from "react";
      const importMap = {};

      imports.forEach(importName => {
        if (!importMap[importName]) {
          importMap[importName] = addNamed(
            path,
            importName,
            getSource(state.source, importName),
            {
              importedInterop: "uncompiled",
              ensureLiveReference: true,
            },
          ).name;
        }
      });

      return importMap;
    } else {
      const importMap = {};
      const sourceMap = {};
      imports.forEach(importName => {
        const source = getSource(state.source, importName);
        if (!importMap[importName]) {
          if (!sourceMap[source]) {
            // var _react = require("react")
            sourceMap[source] = addNamespace(path, source, {
              importedInterop: "uncompiled",
              ensureLiveReference: true,
            }).name;
          }

          importMap[importName] = sourceMap[source];
        }
      });
      return importMap;
    }
  }

  function createIdentifierParser(id) {
    return () => {
      return id
        .split(".")
        .map(name => t.identifier(name))
        .reduce((object, property) => t.memberExpression(object, property));
    };
  }

  function makeTrace(fileNameIdentifier, lineNumber, column0Based) {
    const fileLineLiteral =
      lineNumber != null ? t.numericLiteral(lineNumber) : t.nullLiteral();

    const fileColumnLiteral =
      column0Based != null
        ? t.numericLiteral(column0Based + 1)
        : t.nullLiteral();

    const fileNameProperty = t.objectProperty(
      t.identifier("fileName"),
      fileNameIdentifier,
    );
    const lineNumberProperty = t.objectProperty(
      t.identifier("lineNumber"),
      fileLineLiteral,
    );
    const columnNumberProperty = t.objectProperty(
      t.identifier("columnNumber"),
      fileColumnLiteral,
    );
    return t.objectExpression([
      fileNameProperty,
      lineNumberProperty,
      columnNumberProperty,
    ]);
  }

  function makeSource(path, state) {
    const location = path.node.loc;
    if (!location) {
      // the element was generated and doesn't have location information
      return;
    }

    if (!state.fileNameIdentifier) {
      const { filename = "" } = state;

      const fileNameIdentifier = path.scope.generateUidIdentifier(
        FILE_NAME_VAR,
      );
      const scope = path.hub.getScope();
      if (scope) {
        scope.push({
          id: fileNameIdentifier,
          init: t.stringLiteral(filename),
        });
      }
      state.fileNameIdentifier = fileNameIdentifier;
    }

    return makeTrace(
      state.fileNameIdentifier,
      location.start.line,
      location.start.column,
    );
  }

  function convertJSXIdentifier(node, parent) {
    if (t.isJSXIdentifier(node)) {
      if (node.name === "this" && t.isReferenced(node, parent)) {
        return t.thisExpression();
      } else if (t.isValidIdentifier(node.name, false)) {
        node.type = "Identifier";
      } else {
        return t.stringLiteral(node.name);
      }
    } else if (t.isJSXMemberExpression(node)) {
      return t.memberExpression(
        convertJSXIdentifier(node.object, node),
        convertJSXIdentifier(node.property, node),
      );
    } else if (t.isJSXNamespacedName(node)) {
      /**
       * If the flag "throwIfNamespace" is false
       * print XMLNamespace like string literal
       */
      return t.stringLiteral(`${node.namespace.name}:${node.name.name}`);
    }

    return node;
  }

  function convertAttributeValue(node) {
    if (t.isJSXExpressionContainer(node)) {
      return node.expression;
    } else {
      return node;
    }
  }

  function convertAttribute(node) {
    const value = convertAttributeValue(node.value || t.booleanLiteral(true));

    if (t.isJSXSpreadAttribute(node)) {
      return t.spreadElement(node.argument);
    }

    if (t.isStringLiteral(value) && !t.isJSXExpressionContainer(node.value)) {
      value.value = value.value.replace(/\n\s+/g, " ");

      // "raw" JSXText should not be used from a StringLiteral because it needs to be escaped.
      if (value.extra && value.extra.raw) {
        delete value.extra.raw;
      }
    }

    if (t.isJSXNamespacedName(node.name)) {
      node.name = t.stringLiteral(
        node.name.namespace.name + ":" + node.name.name.name,
      );
    } else if (t.isValidIdentifier(node.name.name, false)) {
      node.name.type = "Identifier";
    } else {
      node.name = t.stringLiteral(node.name.name);
    }

    return t.inherits(t.objectProperty(node.name, value), node);
  }

  // Builds JSX into:
  // Production: React.jsx(type, arguments, key)
  // Development: React.jsxDEV(type, arguments, key, isStaticChildren, source, self)
  function buildJSXElementCall(path, file) {
    const openingPath = path.get("openingElement");
    openingPath.parent.children = t.react.buildChildren(openingPath.parent);

    const tagExpr = convertJSXIdentifier(
      openingPath.node.name,
      openingPath.node,
    );
    const args = [];

    let tagName;
    if (t.isIdentifier(tagExpr)) {
      tagName = tagExpr.name;
    } else if (t.isLiteral(tagExpr)) {
      tagName = tagExpr.value;
    }

    const state = {
      tagExpr: tagExpr,
      tagName: tagName,
      args: args,
      pure: false,
    };

    if (options.pre) {
      options.pre(state, file);
    }

    let attribs = [];
    const extracted = Object.create(null);

    // for React.jsx, key, __source (dev), and __self (dev) is passed in as
    // a separate argument rather than in the args object. We go through the
    // props and filter out these three keywords so we can pass them in
    // as separate arguments later
    for (const attr of openingPath.get("attributes")) {
      if (attr.isJSXAttribute() && t.isJSXIdentifier(attr.node.name)) {
        const { name } = attr.node.name;
        switch (name) {
          case "__source":
          case "__self":
            if (extracted[name]) throw sourceSelfError(path, name);
          /* falls through */
          case "key":
            extracted[name] = convertAttributeValue(attr.node.value);
            break;
          default:
            attribs.push(attr.node);
        }
      } else {
        attribs.push(attr.node);
      }
    }

    if (attribs.length || path.node.children.length) {
      attribs = buildJSXOpeningElementAttributes(
        attribs,
        file,
        path.node.children,
      );
    } else {
      // attributes should never be null
      attribs = t.objectExpression([]);
    }

    args.push(attribs);

    if (!options.development) {
      if (extracted.key !== undefined) {
        args.push(extracted.key);
      }
    } else {
      // isStaticChildren, __source, and __self are only used in development
      // automatically include __source and __self in this plugin
      // so we can eliminate the need for separate Babel plugins in Babel 8
      args.push(
        extracted.key ?? path.scope.buildUndefinedNode(),
        t.booleanLiteral(path.node.children.length > 1),
        extracted.__source ?? path.scope.buildUndefinedNode(),
        extracted.__self ?? t.thisExpression(),
      );
    }

    if (options.post) {
      options.post(state, file);
    }

    const call =
      state.call ||
      t.callExpression(
        path.node.children.length > 1 ? state.jsxStaticCallee : state.jsxCallee,
        args,
      );
    if (state.pure) annotateAsPure(call);

    return call;
  }

  // Builds props for React.jsx. This function adds children into the props
  // and ensures that props is always an object
  function buildJSXOpeningElementAttributes(attribs, file, children) {
    const props = attribs.map(convertAttribute);

    // In React.jsx, children is no longer a separate argument, but passed in
    // through the argument object
    if (children && children.length > 0) {
      if (children.length === 1) {
        props.push(t.objectProperty(t.identifier("children"), children[0]));
      } else {
        props.push(
          t.objectProperty(
            t.identifier("children"),
            t.arrayExpression(children),
          ),
        );
      }
    }

    return t.objectExpression(props);
  }

  // Builds JSX Fragment <></> into
  // Production: React.jsx(type, arguments)
  // Development: React.jsxDEV(type, { children})
  function buildJSXFragmentCall(path, file) {
    const openingPath = path.get("openingElement");
    openingPath.parent.children = t.react.buildChildren(openingPath.parent);

    const args = [];
    const tagName = null;
    const tagExpr = file.get("@babel/plugin-react-jsx/jsxFragIdentifier")();

    const state = {
      tagExpr: tagExpr,
      tagName: tagName,
      args: args,
      pure: false,
    };

    if (options.pre) {
      options.pre(state, file);
    }

    let childrenNode;
    if (path.node.children.length > 0) {
      if (path.node.children.length === 1) {
        childrenNode = path.node.children[0];
      } else {
        childrenNode = t.arrayExpression(path.node.children);
      }
    }

    args.push(
      t.objectExpression(
        childrenNode !== undefined
          ? [t.objectProperty(t.identifier("children"), childrenNode)]
          : [],
      ),
    );

    if (options.development) {
      args.push(
        path.scope.buildUndefinedNode(),
        t.booleanLiteral(path.node.children.length > 1),
      );
    }

    if (options.post) {
      options.post(state, file);
    }

    const call =
      state.call ||
      t.callExpression(
        path.node.children.length > 1 ? state.jsxStaticCallee : state.jsxCallee,
        args,
      );
    if (state.pure) annotateAsPure(call);

    return call;
  }

  function buildCreateElementFragmentCall(path, file) {
    if (options.filter && !options.filter(path.node, file)) {
      return;
    }

    const openingPath = path.get("openingElement");
    openingPath.parent.children = t.react.buildChildren(openingPath.parent);

    const args = [];
    const tagName = null;
    const tagExpr = file.get("@babel/plugin-react-jsx/jsxFragIdentifier")();

    const state = {
      tagExpr: tagExpr,
      tagName: tagName,
      args: args,
      pure: false,
    };

    if (options.pre) {
      options.pre(state, file);
    }

    // no attributes are allowed with <> syntax
    args.push(t.nullLiteral(), ...path.node.children);

    if (options.post) {
      options.post(state, file);
    }

    file.set("@babel/plugin-react-jsx/usedFragment", true);

    const call =
      state.call || t.callExpression(state.createElementCallee, args);
    if (state.pure) annotateAsPure(call);

    return call;
  }

  // Builds JSX into:
  // Production: React.createElement(type, arguments, children)
  // Development: React.createElement(type, arguments, children, source, self)
  function buildCreateElementCall(path, file) {
    const openingPath = path.get("openingElement");
    openingPath.parent.children = t.react.buildChildren(openingPath.parent);

    const tagExpr = convertJSXIdentifier(
      openingPath.node.name,
      openingPath.node,
    );
    const args = [];

    let tagName;
    if (t.isIdentifier(tagExpr)) {
      tagName = tagExpr.name;
    } else if (t.isLiteral(tagExpr)) {
      tagName = tagExpr.value;
    }

    const state = {
      tagExpr: tagExpr,
      tagName: tagName,
      args: args,
      pure: false,
    };

    if (options.pre) {
      options.pre(state, file);
    }

    const attribs = buildCreateElementOpeningElementAttributes(
      path,
      openingPath.node.attributes,
    );

    args.push(attribs, ...path.node.children);

    if (options.post) {
      options.post(state, file);
    }

    const call =
      state.call || t.callExpression(state.createElementCallee, args);
    if (state.pure) annotateAsPure(call);

    return call;
  }

  /**
   * The logic for this is quite terse. It's because we need to
   * support spread elements. We loop over all attributes,
   * breaking on spreads, we then push a new object containing
   * all prior attributes to an array for later processing.
   */
  function buildCreateElementOpeningElementAttributes(path, attribs) {
    const props = [];
    const found = Object.create(null);

    for (const attr of attribs) {
      const name =
        t.isJSXAttribute(attr) &&
        t.isJSXIdentifier(attr.name) &&
        attr.name.name;

      if (name === "__source" || name === "__self") {
        if (found[name]) throw sourceSelfError(path, name);
        found[name] = true;
        if (!options.development) continue;
      }

      props.push(convertAttribute(attr));
    }

    return props.length > 0 ? t.objectExpression(props) : t.nullLiteral();
  }

  function sourceSelfError(path, name) {
    const pluginName = `transform-react-jsx-${name.slice(2)}`;

    return path.buildCodeFrameError(
      `Duplicate ${name} prop found. You are most likely using the deprecated ${pluginName} Babel plugin. Both __source and __self are automatically set when using the automatic runtime. Please remove transform-react-jsx-source and transform-react-jsx-self from your Babel config.`,
    );
  }
}