@react-native/codegen/lib/generators/components/GenerateEventEmitterH.js.flow

Code generation tools for React Native

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow strict-local
 * @format
 */

'use strict';

import type {
  ComponentShape,
  EventTypeAnnotation,
  EventTypeShape,
  NamedShape,
  SchemaType,
} from '../../CodegenSchema';

const {indent, toSafeCppString} = require('../Utils');
const {
  generateEventStructName,
  getCppArrayTypeForAnnotation,
  getCppTypeForAnnotation,
  getImports,
} = require('./CppHelpers');
const nullthrows = require('nullthrows');

// File path -> contents
type FilesOutput = Map<string, string>;
type StructsMap = Map<string, string>;

type ComponentCollection = $ReadOnly<{
  [component: string]: ComponentShape,
  ...
}>;

const FileTemplate = ({
  componentEmitters,
  extraIncludes,
}: {
  componentEmitters: string,
  extraIncludes: Set<string>,
}) => `
/**
 * This code was generated by [react-native-codegen](https://www.npmjs.com/package/react-native-codegen).
 *
 * Do not edit this file as changes may cause incorrect behavior and will be lost
 * once the code is regenerated.
 *
 * ${'@'}generated by codegen project: GenerateEventEmitterH.js
 */
#pragma once

#include <react/renderer/components/view/ViewEventEmitter.h>
${[...extraIncludes].join('\n')}

namespace facebook::react {
${componentEmitters}
} // namespace facebook::react
`;

const ComponentTemplate = ({
  className,
  structs,
  events,
}: {
  className: string,
  structs: string,
  events: string,
}) =>
  `
class ${className}EventEmitter : public ViewEventEmitter {
 public:
  using ViewEventEmitter::ViewEventEmitter;

  ${structs}
  ${events}
};
`.trim();

const StructTemplate = ({
  structName,
  fields,
}: {
  structName: string,
  fields: string,
}) =>
  `
  struct ${structName} {
    ${fields}
  };
`.trim();

const EnumTemplate = ({
  enumName,
  values,
  toCases,
}: {
  enumName: string,
  values: string,
  toCases: string,
}) =>
  `enum class ${enumName} {
  ${values}
};

static char const *toString(const ${enumName} value) {
  switch (value) {
    ${toCases}
  }
}
`.trim();

function getNativeTypeFromAnnotation(
  componentName: string,
  eventProperty: NamedShape<EventTypeAnnotation>,
  nameParts: $ReadOnlyArray<string>,
): string {
  const {type} = eventProperty.typeAnnotation;

  switch (type) {
    case 'BooleanTypeAnnotation':
    case 'StringTypeAnnotation':
    case 'Int32TypeAnnotation':
    case 'DoubleTypeAnnotation':
    case 'FloatTypeAnnotation':
    case 'MixedTypeAnnotation':
      return getCppTypeForAnnotation(type);
    case 'StringLiteralUnionTypeAnnotation':
    case 'ObjectTypeAnnotation':
      return generateEventStructName([...nameParts, eventProperty.name]);
    case 'ArrayTypeAnnotation':
      const eventTypeAnnotation = eventProperty.typeAnnotation;
      if (eventTypeAnnotation.type !== 'ArrayTypeAnnotation') {
        throw new Error(
          "Inconsistent Codegen state: type was ArrayTypeAnnotation at the beginning of the body and now it isn't",
        );
      }
      return getCppArrayTypeForAnnotation(eventTypeAnnotation.elementType, [
        ...nameParts,
        eventProperty.name,
      ]);
    default:
      (type: empty);
      throw new Error(`Received invalid event property type ${type}`);
  }
}
function generateEnum(
  structs: StructsMap,
  options: $ReadOnlyArray<string>,
  nameParts: Array<string>,
) {
  const structName = generateEventStructName(nameParts);
  const fields = options
    .map((option, index) => `${toSafeCppString(option)}`)
    .join(',\n  ');

  const toCases = options
    .map(
      option =>
        `case ${structName}::${toSafeCppString(option)}: return "${option}";`,
    )
    .join('\n' + '    ');

  structs.set(
    structName,
    EnumTemplate({
      enumName: structName,
      values: fields,
      toCases: toCases,
    }),
  );
}

function handleGenerateStructForArray(
  structs: StructsMap,
  name: string,
  componentName: string,
  elementType: EventTypeAnnotation,
  nameParts: $ReadOnlyArray<string>,
): void {
  if (elementType.type === 'ObjectTypeAnnotation') {
    generateStruct(
      structs,
      componentName,
      nameParts.concat([name]),
      nullthrows(elementType.properties),
    );
  } else if (elementType.type === 'StringLiteralUnionTypeAnnotation') {
    generateEnum(
      structs,
      elementType.types.map(literal => literal.value),
      nameParts.concat([name]),
    );
  } else if (elementType.type === 'ArrayTypeAnnotation') {
    handleGenerateStructForArray(
      structs,
      name,
      componentName,
      elementType.elementType,
      nameParts,
    );
  }
}

function generateStruct(
  structs: StructsMap,
  componentName: string,
  nameParts: $ReadOnlyArray<string>,
  properties: $ReadOnlyArray<NamedShape<EventTypeAnnotation>>,
): void {
  const structNameParts = nameParts;
  const structName = generateEventStructName(structNameParts);

  const fields = properties
    .map(property => {
      return `${getNativeTypeFromAnnotation(
        componentName,
        property,
        structNameParts,
      )} ${property.name};`;
    })
    .join('\n' + '  ');

  properties.forEach(property => {
    const {name, typeAnnotation} = property;
    switch (typeAnnotation.type) {
      case 'BooleanTypeAnnotation':
      case 'StringTypeAnnotation':
      case 'Int32TypeAnnotation':
      case 'DoubleTypeAnnotation':
      case 'FloatTypeAnnotation':
      case 'MixedTypeAnnotation':
        return;
      case 'ArrayTypeAnnotation':
        handleGenerateStructForArray(
          structs,
          name,
          componentName,
          typeAnnotation.elementType,
          nameParts,
        );
        return;
      case 'ObjectTypeAnnotation':
        generateStruct(
          structs,
          componentName,
          nameParts.concat([name]),
          nullthrows(typeAnnotation.properties),
        );
        return;
      case 'StringLiteralUnionTypeAnnotation':
        generateEnum(
          structs,
          typeAnnotation.types.map(literal => literal.value),
          nameParts.concat([name]),
        );
        return;
      default:
        (typeAnnotation.type: empty);
        throw new Error(
          `Received invalid event property type ${typeAnnotation.type}`,
        );
    }
  });

  structs.set(
    structName,
    StructTemplate({
      structName,
      fields,
    }),
  );
}

function generateStructs(
  componentName: string,
  component: ComponentShape,
): string {
  const structs: StructsMap = new Map();

  component.events.forEach(event => {
    if (event.typeAnnotation.argument) {
      generateStruct(
        structs,
        componentName,
        [event.name],
        event.typeAnnotation.argument.properties,
      );
    }
  });

  return Array.from(structs.values()).join('\n\n');
}

function generateEvent(componentName: string, event: EventTypeShape): string {
  if (event.typeAnnotation.argument) {
    const structName = generateEventStructName([event.name]);

    return `void ${event.name}(${structName} value) const;`;
  }

  return `void ${event.name}() const;`;
}
function generateEvents(
  componentName: string,
  component: ComponentShape,
): string {
  return component.events
    .map(event => generateEvent(componentName, event))
    .join('\n\n' + '  ');
}

module.exports = {
  generate(
    libraryName: string,
    schema: SchemaType,
    packageName?: string,
    assumeNonnull: boolean = false,
    headerPrefix?: string,
  ): FilesOutput {
    const moduleComponents: ComponentCollection = Object.keys(schema.modules)
      .map(moduleName => {
        const module = schema.modules[moduleName];
        if (module.type !== 'Component') {
          return null;
        }

        const {components} = module;
        // No components in this module
        if (components == null) {
          return null;
        }

        return components;
      })
      .filter(Boolean)
      // $FlowFixMe[unsafe-object-assign]
      .reduce((acc, components) => Object.assign(acc, components), {});

    const extraIncludes = new Set<string>();
    const componentEmitters = Object.keys(moduleComponents)
      .map(componentName => {
        const component = moduleComponents[componentName];

        component.events.forEach(event => {
          if (event.typeAnnotation.argument) {
            const argIncludes = getImports(
              event.typeAnnotation.argument.properties,
            );
            // $FlowFixMe[method-unbinding]
            argIncludes.forEach(extraIncludes.add, extraIncludes);
          }
        });

        const replacedTemplate = ComponentTemplate({
          className: componentName,
          structs: indent(generateStructs(componentName, component), 2),
          events: generateEvents(componentName, component),
        });

        return replacedTemplate;
      })
      .join('\n');

    const fileName = 'EventEmitters.h';
    const replacedTemplate = FileTemplate({
      componentEmitters,
      extraIncludes,
    });

    return new Map([[fileName, replacedTemplate]]);
  },
};