Boolean Schema

Boolean schema

pvl.boolean() accepts true and false. It has no Constraints, only the Shared Modifiers.

const accepted = pvl.boolean();

accepted.validate(true); // { value: true }
accepted.validate('true'); // { issues: [{ code: 'INVALID_TYPE', message: 'Expected boolean' }] }

At a glance

flowchart LR
    subgraph Interpreted
        direction TB
        I1["BooleanInterpretedSchema<br/>no Local Modifier"] --> I2["_checkType:<br/>typeof value !== 'boolean'?"]
    end
    subgraph Compiled
        direction TB
        C1["one _validate"] --> C2["if (typeof value !== 'boolean') push"]
    end

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Interpreted

BooleanInterpretedSchema runs the interpreted pipeline. Its own parts:

• _checkType: typeof value !== 'boolean' reports INVALID_TYPE, "Expected boolean".
• _coerceInput: coerceToBoolean, for .coerce(): a string, number or bigint becomes Boolean(value). That is JavaScript truthiness, so every non-empty string, 'false' included, becomes true.

flowchart TD
    V["_validate(value, path)"] --> PRE["pre-modifiers:<br/>.optional() .nullable() .coerce()"]
    PRE --> TC{"_checkType:<br/>typeof value === 'boolean'?"}
    TC -- no --> F["return { issues: [INVALID_TYPE 'Expected boolean'] }"]
    TC -- yes --> POST["post-modifiers: .refine(), .transform()"]
    POST --> END{"any Issue?"}
    END -- yes --> RI["{ issues }"]
    END -- no --> RV["{ value }"]

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Compiled

What the compiler does

readSchema reads pvl.boolean() into a BooleanSchema. BooleanSchemaEmitter has no postModifierChecks of its own, only the ones it inherits (.refine()).

flowchart TD
    R["readSchema: pvl.boolean()"] --> S["BooleanSchema<br/>calls: []"]
    S --> E["BooleanSchemaEmitter"]
    E --> BC["_emitBaseCheck:<br/>typeof value !== 'boolean'"]
    E --> CO["_emitCoercion (only with .coerce()):<br/>for a string, number or bigint:<br/>value = Boolean(value);"]
    BC --> FR["Frame.composeChecks"]
    CO --> FR

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What the emitted code does

pvl.compile(pvl.boolean()) compiles to:

_validate(value: unknown, path: ReadonlyArray<PropertyKey>): PvlResult<unknown> {
  const issues: PvlIssue[] = [];
  if (typeof value !== "boolean") {
    issues.push({ code: "INVALID_TYPE", message: "Expected boolean", path: path.length > 0 ? path : undefined });
  }
  return issues.length > 0 ? { issues } : { value };
}

With no post-modifier, the base check has no else.

flowchart TD
    S["issues = []"] --> T{"typeof value !== 'boolean'?"}
    T -- yes --> P1["push INVALID_TYPE"] --> RET
    T -- no --> RET["return { issues } or { value }"]

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Local Modifiers

None.

Source

• booleanInterpretedSchema.ts: BooleanInterpretedSchema, BOOLEAN_SCHEMA_ISSUE_MESSAGE
• schemas/booleanSchema.ts: BooleanSchema
• emitters/booleanSchemaEmitter.ts: BooleanSchemaEmitter

Further reading: schema-types.md.