typescript-node-ids v0.0.2

TypeScript support for naming Nodes uniquely and query them. This is particularly useful when modifying the nodes in an iteration and quickly query them again in libraries like ts-simple-ast. In pure TypeScript API this is not so useful since ts APIs for modifications (transformation, replaceText, etc) always generate new SourceFile and nodes, but in other libraries like ts-simple-ast where you can modify the same AST when visiting its nodes, the AST get's deprecated with some modifications and having this feature is useful.

See https://github.com/dsherret/ts-simple-ast/issues/351

import {install, getNodeById, getId} from 'ts-node-ids'

install(sourceFile)

visitAllDescendants(sourceFile, (node=>{if(someCondition(node)){targets.push(getId(node))}})

// later...
targets.forEach(id=>modifNodeSomeHow(getNodeById(sourceFile, id)))

will iterate recursively through given file and add ids to all nodes in the format ${parentId}.${counter} so they are unique and easy / cheap to query

Impl notes

• we cannot reuse typescript implementation for ts-simple-ast implementation since tsNode.compilerNode are changed all the time and we cannot be notified when this happens

TODO

Automatically detect AST modifications

• maybe having a richer key that includes the node kind is more powerfull - if you delete a method other class members keys, like attributes, will still be valid.
  • isValid(node) 1) store a map in the node per kind and counter of chid nodes of that kind. 2) then we have a way of knowing if user removed / added new nodes and exactly where so we can re-install ids automatically for example cache invalidation
  • will this work when user changes values like id.text ? is that possible ?

Cache

• getById with cache ? and api for invalidation ? - if key is a.b.c.d we can check cache for a.b.c or a.b or a first.

Performance

• implement visit_getChildren probably faster - always pass sourcefile !
• benchmark and compare visit_getChildren against visit_forEachChild

other

• support ts-simple-ast that's where this make sense - but probably in a separate lib dependant on this one