time-to-botec/squiggle/node_modules/@stdlib/utils/library-manifest/README.md

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# Manifest

> Load a manifest for compiling source files.

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</section>

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## Usage

```javascript
var manifest = require( '@stdlib/utils/library-manifest' );
```

#### manifest( filepath, conditions\[, options] )

Loads a manifest for compiling source files.

```javascript
var conditions = {
    'os': 'linux'
};

var conf = manifest( './examples/manifest.json', conditions );
// returns <Object>
```

The function accepts the following `options`:

-   **basedir**: base directory from which to search for dependencies. Default: current working directory.
-   **paths**: path convention. Must be either `'win32'`, `'mixed'`, or `'posix'`. Default: based on host platform.

The default search directory is the current working directory of the calling process. To specify an alternative search directory, set the `basedir` option.

```javascript
var conditions = {
    'os': 'linux'
};

var opts = {
    'basedir': __dirname
};

var conf = manifest( './examples/manifest.json', conditions, opts );
// returns <Object>
```

</section>

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## Notes

-   A _manifest_ is a [JSON][json] file having the following fields:

    -   **options**: an `object` containing key-value pairs. Each key corresponds to a field in **confs** and may be used to conditionally select a configuration. Each value corresponds to the key's default value. The value for each field in a provided `conditions` object which has a corresponding field in **options** overrides the default value.

        Option keys are akin to primary keys in relational databases, in the sense that they should be used to uniquely identify a particular configuration. While individual key values may be shared across configurations, each configuration should have a unique combination of key values. Furthermore, default option values considered as a unique set should identify one and only one default configuration.

    -   **fields**: an object `array` where each `object` has the following fields:

        -   **field**: key name corresponding to a field in **confs**.
        -   **resolve**: `boolean` indicating whether to resolve field values as file paths. If `true`, all field values are resolved relative to the manifest file.
        -   **relative**: `boolean` indicating whether to resolve field values as relative file paths. This field is **only** considered when a manifest is a root manifest. If `true`, all field values, including those originating from dependencies, are resolved as relative file paths relative the root manifest.

    -   **confs**: an object `array` where each `object` corresponds to a manifest configuration. Each `object` has the following fields:

        -   **src**: `array` of source files.
        -   **include**: `array` of include directories.
        -   **libraries**: `array` of linked library dependencies.
        -   **libpath**: `array` of linked library paths.
        -   **dependencies**: `array` of package dependencies containing source files.

    An example _manifest_:

    ```text
    {
      "options": {
        "os": "linux"
      },
      "fields": [
        {
          "field": "src",
          "resolve": true,
          "relative": true
        },
        {
          "field": "include",
          "resolve": true,
          "relative": false
        },
        {
          "field": "libraries",
          "resolve": false,
          "relative": false
        },
        {
          "field": "libpath",
          "resolve": true,
          "relative": false
        }
      ],
      "confs": [
        {
          "os": "linux",
          "src": [
            "./src/foo_linux.f",
            "./src/foo_linux.c"
          ],
          "include": [
            "./include"
          ],
          "libraries": [],
          "libpath": [],
          "dependencies": [
            "@stdlib/blas/base/daxpy",
            "@stdlib/blas/base/dasum",
            "@stdlib/blas/base/dcopy"
          ]
        }
      ]
    }   
    ```

-   The function recursively walks the manifest dependency tree to resolve **all** source files, libraries, library paths, and include directories.

-   An input `filepath` may be either a relative or absolute file path. If provided a relative file path, a manifest is resolved relative to the base search directory.

-   If a `conditions` object contains fields which do not correspond to manifest options, those fields are ignored (i.e., the "extra" fields have no effect when filtering manifest configurations). This allows providing a `conditions` object containing fields which only apply to certain subsets of manifest dependencies.

-   If no fields in a `conditions` object have corresponding fields in a manifest's options, the function returns a manifest's default configuration.

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## Examples

<!-- eslint no-undef: "error" -->

```javascript
var join = require( 'path' ).join;
var manifest = require( '@stdlib/utils/library-manifest' );

// Resolve the absolute path of the manifest JSON file:
var fpath = join( __dirname, 'examples', 'manifest.json' );

// Specify conditions for determining which configuration to load:
var conditions = {
    'os': 'mac'
};

// Specify options:
var opts = {
    'basedir': __dirname
};

// Load a manifest configuration:
var conf = manifest( fpath, conditions, opts );
console.dir( conf );
```

</section>

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* * *

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## CLI

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### Usage

```text
Usage: library-manifest [options] <filepath> [-- --<condition>=value ...]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --dir basedir         Base search directory.
         --paths convention    Path convention.
```

</section>

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### Notes

-   Use command-line flags to specify conditions by placing them after a `--` separator.

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### Examples

```bash
$ library-manifest ./examples/manifest.json -- --os mac
```

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</section>

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[json]: http://www.json.org/

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