create-plugin.js

import jsx from "@babel/plugin-syntax-jsx";
import { declare } from "@babel/helper-plugin-utils";
import { types as t } from "@babel/core";
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",
};

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]+)/;

const get = (pass, name) => pass.get(`@babel/plugin-react-jsx/${name}`);
const set = (pass, name, v) => pass.set(`@babel/plugin-react-jsx/${name}`, v);

export default function createPlugin({ name, development }) {
  return declare((api, options) => {
    const {
      pure: PURE_ANNOTATION,

      throwIfNamespace = true,

      // TODO (Babel 8): It should throw if this option is used with the automatic runtime
      filter,

      runtime: RUNTIME_DEFAULT = process.env.BABEL_8_BREAKING
        ? "automatic"
        : development
        ? "automatic"
        : "classic",

      importSource: IMPORT_SOURCE_DEFAULT = DEFAULT.importSource,
      pragma: PRAGMA_DEFAULT = DEFAULT.pragma,
      pragmaFrag: PRAGMA_FRAG_DEFAULT = DEFAULT.pragmaFrag,
    } = options;

    if (process.env.BABEL_8_BREAKING) {
      if ("useSpread" in options) {
        throw new Error(
          '@babel/plugin-transform-react-jsx: Since Babel 8, an inline object with spread elements is always used, and the "useSpread" option is no longer available. Please remove it from your config.',
        );
      }

      if ("useBuiltIns" in options) {
        const useBuiltInsFormatted = JSON.stringify(options.useBuiltIns);
        throw new Error(
          `@babel/plugin-transform-react-jsx: Since "useBuiltIns" is removed in Babel 8, you can remove it from the config.
- Babel 8 now transforms JSX spread to object spread. If you need to transpile object spread with
\`useBuiltIns: ${useBuiltInsFormatted}\`, you can use the following config
{
  "plugins": [
    "@babel/plugin-transform-react-jsx"
    ["@babel/plugin-proposal-object-rest-spread", { "loose": true, "useBuiltIns": ${useBuiltInsFormatted} }]
  ]
}`,
        );
      }
    } else {
      // eslint-disable-next-line no-var
      var { useSpread = false, useBuiltIns = false } = options;

      if (RUNTIME_DEFAULT === "classic") {
        if (typeof useSpread !== "boolean") {
          throw new Error(
            "transform-react-jsx currently only accepts a boolean option for " +
              "useSpread (defaults to false)",
          );
        }

        if (typeof useBuiltIns !== "boolean") {
          throw new Error(
            "transform-react-jsx currently only accepts a boolean option for " +
              "useBuiltIns (defaults to false)",
          );
        }

        if (useSpread && useBuiltIns) {
          throw new Error(
            "transform-react-jsx currently only accepts useBuiltIns or useSpread " +
              "but not both",
          );
        }
      }
    }

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

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

    return {
      name,
      inherits: jsx,
      visitor: {
        JSXNamespacedName(path) {
          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.",
          );
        },

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

            let source = IMPORT_SOURCE_DEFAULT;
            let pragma = PRAGMA_DEFAULT;
            let pragmaFrag = PRAGMA_FRAG_DEFAULT;

            let sourceSet = !!options.importSource;
            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;
                }
              }
            }

            set(state, "runtime", runtime);
            if (runtime === "classic") {
              if (sourceSet) {
                throw path.buildCodeFrameError(
                  `importSource cannot be set when runtime is classic.`,
                );
              }

              const createElement = toMemberExpression(pragma);
              const fragment = toMemberExpression(pragmaFrag);

              set(state, "id/createElement", () => t.cloneNode(createElement));
              set(state, "id/fragment", () => t.cloneNode(fragment));

              set(state, "defaultPure", pragma === DEFAULT.pragma);
            } else if (runtime === "automatic") {
              if (pragmaSet || pragmaFragSet) {
                throw path.buildCodeFrameError(
                  `pragma and pragmaFrag cannot be set when runtime is automatic.`,
                );
              }

              const define = (name, id) =>
                set(state, name, createImportLazily(state, path, id, source));

              define("id/jsx", development ? "jsxDEV" : "jsx");
              define("id/jsxs", development ? "jsxDEV" : "jsxs");
              define("id/createElement", "createElement");
              define("id/fragment", "Fragment");

              set(state, "defaultPure", source === DEFAULT.importSource);
            } else {
              throw path.buildCodeFrameError(
                `Runtime must be either "classic" or "automatic".`,
              );
            }

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

          // TODO (Babel 8): Decide if this should be removed or brought back.
          // see: https://github.com/babel/babel/pull/12253#discussion_r513086528
          //
          // exit(path, state) {
          //   if (
          //     get(state, "runtime") === "classic" &&
          //     get(state, "pragmaSet") &&
          //     get(state, "usedFragment") &&
          //     !get(state, "pragmaFragSet")
          //   ) {
          //     throw new Error(
          //       "transform-react-jsx: pragma has been set but " +
          //         "pragmaFrag has not been set",
          //     );
          //   }
          // },
        },

        JSXElement: {
          exit(path, file) {
            let callExpr;
            if (
              get(file, "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 (get(file, "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);
          }
        },
      },
    };

    function call(pass, name, args) {
      const node = t.callExpression(get(pass, `id/${name}`)(), args);
      if (PURE_ANNOTATION ?? get(pass, "defaultPure")) annotateAsPure(node);
      return node;
    }

    // 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 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 accumulateAttribute(array, attribute) {
      if (t.isJSXSpreadAttribute(attribute.node)) {
        const arg = attribute.node.argument;
        // Collect properties into props array if spreading object expression
        if (t.isObjectExpression(arg)) {
          array.push(...arg.properties);
        } else {
          array.push(t.spreadElement(arg));
        }
        return array;
      }

      const value = convertAttributeValue(
        attribute.node.name.name !== "key"
          ? attribute.node.value || t.booleanLiteral(true)
          : attribute.node.value,
      );

      if (attribute.node.name.name === "key" && value === null) {
        throw attribute.buildCodeFrameError(
          'Please provide an explicit key value. Using "key" as a shorthand for "key={true}" is not allowed.',
        );
      }

      if (
        t.isStringLiteral(value) &&
        !t.isJSXExpressionContainer(attribute.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.
        delete value.extra?.raw;
      }

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

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

    function buildChildrenProperty(children) {
      let childrenNode;
      if (children.length === 1) {
        childrenNode = children[0];
      } else if (children.length > 1) {
        childrenNode = t.arrayExpression(children);
      } else {
        return undefined;
      }

      return t.objectProperty(t.identifier("children"), childrenNode);
    }

    // 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");
      const args = [getTag(openingPath)];

      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": {
              const keyValue = convertAttributeValue(attr.node.value);
              if (keyValue === null) {
                throw attr.buildCodeFrameError(
                  'Please provide an explicit key value. Using "key" as a shorthand for "key={true}" is not allowed.',
                );
              }

              extracted[name] = keyValue;
              break;
            }
            default:
              attribs.push(attr);
          }
        } else {
          attribs.push(attr);
        }
      }

      const children = t.react.buildChildren(path.node);

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

      args.push(attribs);

      if (development) {
        // 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(children.length > 1),
          extracted.__source ?? path.scope.buildUndefinedNode(),
          extracted.__self ?? t.thisExpression(),
        );
      } else if (extracted.key !== undefined) {
        args.push(extracted.key);
      }

      return call(file, children.length > 1 ? "jsxs" : "jsx", args);
    }

    // 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.reduce(accumulateAttribute, []);

      // In React.jsx, children is no longer a separate argument, but passed in
      // through the argument object
      if (children?.length > 0) {
        props.push(buildChildrenProperty(children));
      }

      return t.objectExpression(props);
    }

    // Builds JSX Fragment <></> into
    // Production: React.jsx(type, arguments)
    // Development: React.jsxDEV(type, { children })
    function buildJSXFragmentCall(path, file) {
      const args = [get(file, "id/fragment")()];

      const children = t.react.buildChildren(path.node);

      args.push(
        t.objectExpression(
          children.length > 0 ? [buildChildrenProperty(children)] : [],
        ),
      );

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

      return call(file, children.length > 1 ? "jsxs" : "jsx", args);
    }

    // Builds JSX Fragment <></> into
    // React.createElement(React.Fragment, null, ...children)
    function buildCreateElementFragmentCall(path, file) {
      if (filter && !filter(path.node, file)) return;

      return call(file, "createElement", [
        get(file, "id/fragment")(),
        t.nullLiteral(),
        ...t.react.buildChildren(path.node),
      ]);
    }

    // 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");

      return call(file, "createElement", [
        getTag(openingPath),
        buildCreateElementOpeningElementAttributes(
          file,
          path,
          openingPath.get("attributes"),
        ),
        ...t.react.buildChildren(path.node),
      ]);
    }

    function getTag(openingPath) {
      const tagExpr = convertJSXIdentifier(
        openingPath.node.name,
        openingPath.node,
      );

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

      if (t.react.isCompatTag(tagName)) {
        return t.stringLiteral(tagName);
      } else {
        return tagExpr;
      }
    }

    /**
     * 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(file, path, attribs) {
      const runtime = get(file, "runtime");
      if (!process.env.BABEL_8_BREAKING) {
        if (runtime !== "automatic") {
          const objs = [];
          const props = attribs.reduce(accumulateAttribute, []);

          if (!useSpread) {
            // Convert syntax to use multiple objects instead of spread
            let start = 0;
            props.forEach((prop, i) => {
              if (t.isSpreadElement(prop)) {
                if (i > start) {
                  objs.push(t.objectExpression(props.slice(start, i)));
                }
                objs.push(prop.argument);
                start = i + 1;
              }
            });
            if (props.length > start) {
              objs.push(t.objectExpression(props.slice(start)));
            }
          } else if (props.length) {
            objs.push(t.objectExpression(props));
          }

          if (!objs.length) {
            return t.nullLiteral();
          }

          if (objs.length === 1) {
            return objs[0];
          }

          // looks like we have multiple objects
          if (!t.isObjectExpression(objs[0])) {
            objs.unshift(t.objectExpression([]));
          }

          const helper = useBuiltIns
            ? t.memberExpression(t.identifier("Object"), t.identifier("assign"))
            : file.addHelper("extends");

          // spread it
          return t.callExpression(helper, objs);
        }
      }

      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 (
          runtime === "automatic" &&
          (name === "__source" || name === "__self")
        ) {
          if (found[name]) throw sourceSelfError(path, name);
          found[name] = true;
        }

        accumulateAttribute(props, attr);
      }

      return props.length === 1 && t.isSpreadElement(props[0])
        ? props[0].argument
        : props.length > 0
        ? t.objectExpression(props)
        : t.nullLiteral();
    }
  });

  function getSource(source, importName) {
    switch (importName) {
      case "Fragment":
        return `${source}/${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 createImportLazily(pass, path, importName, source) {
    return () => {
      const actualSource = getSource(source, importName);
      if (isModule(path)) {
        let reference = get(pass, `imports/${importName}`);
        if (reference) return t.cloneNode(reference);

        reference = addNamed(path, importName, actualSource, {
          importedInterop: "uncompiled",
          importPosition: "after",
        });
        set(pass, `imports/${importName}`, reference);

        return reference;
      } else {
        let reference = get(pass, `requires/${actualSource}`);
        if (reference) {
          reference = t.cloneNode(reference);
        } else {
          reference = addNamespace(path, actualSource, {
            importedInterop: "uncompiled",
          });
          set(pass, `requires/${actualSource}`, reference);
        }

        return t.memberExpression(reference, t.identifier(importName));
      }
    };
  }
}

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

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

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

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

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

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 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.`,
  );
}