# core/formatters/config.toml.formatter.ts

> 56 lines of code and 15 definitions.

Tree: GovLab Quality
Language: typescript
Layer: processing
Canonical: https://banes-lab.com/anatomy/quality#file-quality-core-formatters-config-toml-formatter-ts
Source text: https://banes-lab.com/source/quality/core/formatters/config.toml.formatter.ts.txt

Listed in [core/formatters](https://banes-lab.com/api/source/quality/core/formatters.md), after [core/formatters/config.ini.formatter.ts](https://banes-lab.com/source/quality/core/formatters/config.ini.formatter.ts.md) and before [core/formatters/config.xml.formatter.ts](https://banes-lab.com/source/quality/core/formatters/config.xml.formatter.ts.md).

## Definitions

- `tomlValue` (lexical_declaration, line 16)
- `scalar` (lexical_declaration, line 6)
- `trimTrailingBlank` (lexical_declaration, line 50)
- `partitionTable` (lexical_declaration, line 26)
- `serializeToml` (lexical_declaration, line 58, exported)
- `items` (lexical_declaration, line 18)
- `scalars` (lexical_declaration, line 30)
- `tables` (lexical_declaration, line 31)
- `emitTable` (lexical_declaration, line 42)
- `{ scalars, tables }` (lexical_declaration, line 43)
- `header` (lexical_declaration, line 44)
- `spacer` (lexical_declaration, line 45)
- `childLines` (lexical_declaration, line 46)
- `end` (lexical_declaration, line 51)
- `out` (lexical_declaration, line 59, exported)

## Contained in

- [core/formatters](https://banes-lab.com/anatomy/quality/folder-quality-core-formatters.md)

## Uses

- [core/predicates/config.predicate.ts](https://banes-lab.com/source/quality/core/predicates/config.predicate.ts.md)

## Linked from

- [core/formatters](https://banes-lab.com/anatomy/quality/folder-quality-core-formatters.md)
- [core/predicates](https://banes-lab.com/anatomy/quality/folder-quality-core-predicates.md)

## Source

```typescript
import type { ConfigValue } from "#types/emitter.types";
import { defineFormatter } from "#core/registries/formatter.registry";
import { isConfigObject } from "#core/predicates/config.predicate";
import { treeFor } from "#core/converters/emitter.converter";

const scalar = function scalar(value: boolean | number | string | null): string {
    if (value === null) {
        return '""';
    }
    if (typeof value === "boolean") {
        return value ? "true" : "false";
    }
    return typeof value === "number" ? String(value) : JSON.stringify(value);
};

const tomlValue = function tomlValue(value: ConfigValue): string {
    if (Array.isArray(value)) {
        const items = value.filter(
            (item): item is boolean | number | string | null => !isConfigObject(item) && !Array.isArray(item),
        );
        return `[${items.map(scalar).join(", ")}]`;
    }
    return isConfigObject(value) ? "{}" : scalar(value);
};

const partitionTable = function partitionTable(obj: Record<string, ConfigValue>): {
    scalars: string[];
    tables: [string, Record<string, ConfigValue>][];
} {
    const scalars: string[] = [];
    const tables: [string, Record<string, ConfigValue>][] = [];
    for (const [key, value] of Object.entries(obj)) {
        if (isConfigObject(value)) {
            tables.push([key, value]);
        } else {
            scalars.push(`${key} = ${tomlValue(value)}`);
        }
    }
    return { scalars, tables };
};

const emitTable = function emitTable(name: string | null, obj: Record<string, ConfigValue>): string[] {
    const { scalars, tables } = partitionTable(obj);
    const header = name === null ? [] : [`[${name}]`];
    const spacer = scalars.length > 0 || name !== null ? [""] : [];
    const childLines = tables.flatMap(([key, sub]) => emitTable(name === null ? key : `${name}.${key}`, sub));
    return [...header, ...scalars, ...spacer, ...childLines];
};

const trimTrailingBlank = function trimTrailingBlank(lines: string[]): string[] {
    let end = lines.length;
    while (end > 0 && lines[end - 1] === "") {
        end -= 1;
    }
    return lines.slice(0, end);
};

export const serializeToml = function serializeToml(tree: ConfigValue): string {
    const out = isConfigObject(tree) ? emitTable(null, tree) : [];
    return `${trimTrailingBlank(out).join("\n")}\n`;
};

defineFormatter({ format: "toml", render: (input) => serializeToml(treeFor(input)) });
```