40 lines
2.2 KiB
TypeScript
Executable File
40 lines
2.2 KiB
TypeScript
Executable File
import type { BlockMap, BlockSequence, CollectionItem, Document, FlowCollection } from './cst';
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export type VisitPath = readonly ['key' | 'value', number][];
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export type Visitor = (item: CollectionItem, path: VisitPath) => number | symbol | Visitor | void;
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/**
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* Apply a visitor to a CST document or item.
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*
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* Walks through the tree (depth-first) starting from the root, calling a
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* `visitor` function with two arguments when entering each item:
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* - `item`: The current item, which included the following members:
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* - `start: SourceToken[]` – Source tokens before the key or value,
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* possibly including its anchor or tag.
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* - `key?: Token | null` – Set for pair values. May then be `null`, if
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* the key before the `:` separator is empty.
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* - `sep?: SourceToken[]` – Source tokens between the key and the value,
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* which should include the `:` map value indicator if `value` is set.
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* - `value?: Token` – The value of a sequence item, or of a map pair.
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* - `path`: The steps from the root to the current node, as an array of
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* `['key' | 'value', number]` tuples.
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*
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* The return value of the visitor may be used to control the traversal:
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* - `undefined` (default): Do nothing and continue
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* - `visit.SKIP`: Do not visit the children of this token, continue with
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* next sibling
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* - `visit.BREAK`: Terminate traversal completely
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* - `visit.REMOVE`: Remove the current item, then continue with the next one
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* - `number`: Set the index of the next step. This is useful especially if
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* the index of the current token has changed.
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* - `function`: Define the next visitor for this item. After the original
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* visitor is called on item entry, next visitors are called after handling
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* a non-empty `key` and when exiting the item.
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*/
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export declare function visit(cst: Document | CollectionItem, visitor: Visitor): void;
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export declare namespace visit {
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var BREAK: symbol;
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var SKIP: symbol;
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var REMOVE: symbol;
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var itemAtPath: (cst: Document | CollectionItem, path: VisitPath) => CollectionItem | undefined;
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var parentCollection: (cst: Document | CollectionItem, path: VisitPath) => BlockMap | BlockSequence | FlowCollection;
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}
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