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78 lines
2.3 KiB
78 lines
2.3 KiB
// @flow
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import assert from 'assert';
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import {isValue, typeOf, Color} from '../values.js';
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import Formatted from '../types/formatted.js';
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import type {Type} from '../types.js';
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import type {Value} from '../values.js';
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import type {Expression, SerializedExpression} from '../expression.js';
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import type ParsingContext from '../parsing_context.js';
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class Literal implements Expression {
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type: Type;
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value: Value;
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constructor(type: Type, value: Value) {
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this.type = type;
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this.value = value;
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}
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static parse(args: $ReadOnlyArray<mixed>, context: ParsingContext): void | Literal {
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if (args.length !== 2)
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return context.error(`'literal' expression requires exactly one argument, but found ${args.length - 1} instead.`);
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if (!isValue(args[1]))
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return context.error(`invalid value`);
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const value = (args[1]: any);
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let type = typeOf(value);
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// special case: infer the item type if possible for zero-length arrays
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const expected = context.expectedType;
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if (
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type.kind === 'array' &&
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type.N === 0 &&
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expected &&
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expected.kind === 'array' &&
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(typeof expected.N !== 'number' || expected.N === 0)
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) {
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type = expected;
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}
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return new Literal(type, value);
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}
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evaluate(): Value {
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return this.value;
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}
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eachChild() {}
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outputDefined(): boolean {
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return true;
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}
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serialize(): SerializedExpression {
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if (this.type.kind === 'array' || this.type.kind === 'object') {
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return ["literal", this.value];
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} else if (this.value instanceof Color) {
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// Constant-folding can generate Literal expressions that you
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// couldn't actually generate with a "literal" expression,
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// so we have to implement an equivalent serialization here
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return ["rgba"].concat(this.value.toArray());
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} else if (this.value instanceof Formatted) {
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// Same as Color
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return this.value.serialize();
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} else {
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assert(this.value === null ||
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typeof this.value === 'string' ||
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typeof this.value === 'number' ||
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typeof this.value === 'boolean');
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return (this.value: any);
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}
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}
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}
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export default Literal;
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