Codama ➤ Renderers ➤ Core

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This package provides the core utility for generating clients from Codama IDLs. Its aim is mainly to provide helpers for other renderer packages such as @codama/renderers-js and @codama/renderers-rust.

Installation

``sh
pnpm install @codama/renderers-core
`

> [!NOTE]
> This package is not included in the main codama package.

Filesystem wrappers

This package offers several helper functions that delegate to the native Filesystem API — i.e. node:fs — when using the Node.js runtime. However, in any other environment — such as the browser — these functions will throw a CODAMA_ERROR__NODE_FILESYSTEM_FUNCTION_UNAVAILABLE error as a Filesystem API is not available. This enables us to import renderers regardless of the runtime environment.

$3

Creates a directory at the given path, recursively.

`ts
createDirectory(newDirectoryPath);
`

$3

Deletes a directory, recursively, if it exists.

`ts
deleteDirectory(directoryPath);
`

$3

Creates a new file at the given path with the given content. Creates its parent directory, recursively, if it does not exist.

`ts
writeFile(filePath, content);
`

$3

Reads the UTF-8 content of a file as a string.

`ts
const content = readFile(filePath);
`

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Reads the UTF-8 content of a file as a JSON object.

`ts
const json = readJson(filePath);
`

Path wrappers

This package also offers several path helpers that delegate to the native node:path module when using the Node.js runtime but provide a fallback implementation when using any other runtime.

$3

Joins multiple path segments into a single path.

`ts
const path = joinPath('path', 'to', 'my', 'file.ts');
`

$3

Returns the parent directory of a given path.

`ts
const parentPath = pathDirectory(path);
`

Fragments

The concept of fragments is commonly used in Codama renderers as a way to combine a piece of code with any context that is relevant to that piece of code. For instance, a fragment may include a dependency map that lists all the module imports required by that piece of code.

Since fragments vary from one renderer to another, this package cannot provide a one-size-fits-all Fragment type. Instead, it provides some base types and utility functions that can be used to build more specific fragment types.

$3

The BaseFragment type is an object that includes a content string. Renderers may extend this type to include any additional context they need.

`ts
type Fragment = BaseFragment & Readonly<{ importMap: ImportMap }>;
`

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The mapFragmentContent helper can be used to transform the content of a fragment while preserving the rest of its context.

`ts
const updatedFragment = mapFragmentContent(fragment, c => /* This is a fragment. /\n${c});
`

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The mapFragmentContentAsync helper can be used to transform the content of a fragment asynchronously while preserving the rest of its context.

`ts
const updatedFragment = mapFragmentContentAsync(fragment, async c => ${await getDocs(c)}\n${c});
`

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The setFragmentContent helper can be used to replace the content of a fragment while preserving the rest of its context.

`ts
const updatedFragment = setFragmentContent(fragment, '[redacted]');
`

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The createFragmentTemplate helper can be used to create tagged template literal functions. For this, you need to provide a function that can merge multiple fragments together and a function that can identify fragments from other values.

`ts
function fragment(template: TemplateStringsArray, ...items: unknown[]): Fragment {
return createFragmentTemplate(template, items, isFragment, mergeFragments);
}
const apple = fragmentapple;
const banana = fragmentbanana;
const fruits = fragment${apple}, ${banana};
`

Render maps

This package also provides a RenderMap type and a handful of helpers to work with it.

A RenderMap is a utility type that helps manage a collection of Fragment files to be rendered. It acts as a middleman between the logic that generates the content and the logic that writes the content to the filesystem. As such, it provides a way to access the generated content outside an environment that supports the Filesystem API — such as the browser. It also helps us write tests about the generated code without having to write it to the filesystem.

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You can use the createRenderMap function with no arguments to create a new empty RenderMap.

`ts
const renderMap = createRenderMap();
`

Since RenderMaps store fragments, you may specify a custom fragment type parameter that extends BaseFragment when creating a new RenderMap.

`ts
type Fragment = BaseFragment & { imports: ImportMap };
const renderMap = createRenderMap();
`

You may provide the path and fragment of a file to create a RenderMap with a single file.

`ts
const renderMap = createRenderMap('path/to/file.ts', { content: 'file content' });
`

You may also provide an object mapping file paths to their fragments to create a RenderMap with multiple files.

`ts
const renderMap = createRenderMap({
'path/to/file.ts': { content: 'file content' },
'path/to/another/file.ts': { content: 'another file content' },
});
`

Note that when setting paths inside a RenderMap, they should be relative to the base directory that will be provided when writing the RenderMap to the filesystem. For instance, if we decide to use src/generated as the base directory when writing the RenderMap, then using a path such as accounts/mint.ts will result in the file being written to src/generated/accounts/mint.ts.

$3

To add content to a RenderMap, you may use the addToRenderMap function by providing the path and the fragment of the file to be added. Note that, here as well, the path should be relative to the base directory that will be provided when writing the RenderMap to the filesystem.

`ts
const updatedRenderMap = addToRenderMap(renderMap, 'path/to/file.ts', { content: 'file content' });
`

Since RenderMaps are immutable, you may want to use the pipe function from @codama/visitors-core — also available in codama — to chain multiple updates together.

`ts
const renderMap = pipe(
createRenderMap(),
m => addToRenderMap(m, 'programs/token.ts', { content: 'export type TokenProgram = {...}' }),
m => addToRenderMap(m, 'accounts/mint.ts', { content: 'export type MintAccount = {...}' }),
m => addToRenderMap(m, 'instructions/transfer.ts', { content: 'export function getTransferInstruction() {...}' }),
);
`

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You may use the mergeRenderMaps helper to combine multiple RenderMap instances into a single one. If two RenderMap instances contain the same file path, the content from the latter will overwrite the content from the former.

`ts
const renderMapA = createRenderMap('programs/programA.ts', { content: 'export type ProgramA = {...}' });
const renderMapB = createRenderMap('programs/programB.ts', { content: 'export type ProgramB = {...}' });
const mergedRenderMap = mergeRenderMaps(renderMapA, renderMapB);
`

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To remove files from a RenderMap, simply use the removeFromRenderMap function by providing the relative path of the file to be removed.

`ts
const updatedRenderMap = removeFromRenderMap(renderMap, 'programs/token.ts');
`

$3

The RenderMap type is essentially a JavaScript Map so you can use all the methods available on the Map prototype. Therefore, you may use the get method to access the content of a file from its relative path.

`ts
const content: string | undefined = renderMap.get('programs/token.ts');
`

However, this may return undefined if the file does not exist on the RenderMap. If you want to access the content of a file and throw an error if it does not exist, you can use the getFromRenderMap helper instead.

`ts
const content: string = getFromRenderMap(renderMap, 'programs/token.ts');
`

You may also use the renderMapContains helper to check if the provided file content exists in the RenderMap at the given path. The expected file content can be a string or a regular expression.

`ts
const hasTokenProgram = renderMapContains(renderMap, 'programs/token.ts', 'export type TokenProgram = {...}');
const hasMintAccount = renderMapContains(renderMap, 'programs/token.ts', /MintAccount/);
`

$3

To map the content of all files inside a RenderMap, you can use the mapRenderMapContent function. This method accepts a function that takes the content of a file and returns a new content.

`ts
const updatedRenderMap = mapRenderMapContent(renderMap, c => /* Prefix for all files /\n\n${c});
`

An asynchronous version of this function called mapRenderMapContentAsync is also available in case the transformation function needs to be asynchronous.

`ts
const updatedRenderMap = await mapRenderMapContentAsync(renderMap, async content => {
const transformedContent = await someAsyncFunction(content);
return /* Prefix for all files /\n\n${transformedContent};
});
`

Note that in both cases, a second argument is available in the mapping function that provides the relative path of the file being transformed.

`ts
const updatedRenderMap = mapRenderMapContent(renderMap, (content, path) => /* File: ${path} /\n\n${content});
`

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When the RenderMap is ready to be written to the filesystem, you can use the writeRenderMap helper by providing the base directory where all files should be written. All paths inside the RenderMap will be appended to this base directory.

`ts
const renderMap = createRenderMap({
'programs/token.ts': { content: 'export type TokenProgram = {...}' },
'accounts/mint.ts': { content: 'export type MintAccount = {...}' },
});

writeRenderMap(renderMap, 'src/generated');
// In this example, files will be written to:
// - src/generated/programs/token.ts
// - src/generated/accounts/mint.ts.
`

$3

When building renderers, you will most likely create a visitor that traverses the Codama IDL and returns a RenderMap. That way, you can test the generated content without having to write it to the filesystem. For instance, the @codama/renderers-js package exports a getRenderMapVisitor function that does just that.

`ts
import { getRenderMapVisitor } from '@codama/renderers-js';

const renderMap = codama.accept(getRenderMapVisitor());
`

If you have access to a visitor that returns a RenderMap — also described as Visitor — then, you can wrap it inside the writeRenderMapVisitor to directly write the content to the filesystem at the given base directory.

`ts
import { getRenderMapVisitor } from '@codama/renderers-js';

codama.accept(writeRenderMapVisitor(getRenderMapVisitor(), 'src/generated'));
`

Note however that, if you are writing your own renderer, you should probably offer a higher-level visitor that includes this logic and also does some additional work such as deleting the base directory before writing the new content if it already exists.

For instance, the recommended way of using the @codama/renderers-js package is to use its default exported visitor which does exactly that.

`ts
import renderVisitor from '@codama/renderers-js';

codama.accept(renderVisitor('src/generated'));
`

Here's a simple example of how to set up the basis of a renderer from an existing getRenderMapVisitor.

`ts
import { deleteDirectory } from '@codama/renderers-core';
import { rootNodeVisitor, visit } from '@codama/visitors-core';

type RenderOptions = {
deleteFolderBeforeRendering?: boolean;
// Any other options...
};

export function renderVisitor(path: string, options: RenderOptions = {}) {
return rootNodeVisitor(async root => {
// Delete existing generated folder.
if (options.deleteFolderBeforeRendering ?? true) {
deleteDirectory(path);
}

// Render the new files.
visit(root, writeRenderMapVisitor(getRenderMapVisitor(options), path));
});
}
``