@thi.ng/parse/readers/string-reader.js

Purely functional parser combinators & AST generation for generic inputs

class StringReader {
  constructor(_src) {
    this._src = _src;
  }
  read(state) {
    return this._src[state.p];
  }
  prev(state) {
    return this._src[state.p - 1];
  }
  next(state) {
    if (state.done) return;
    if (this._src[state.p] === "\n") {
      state.l++;
      state.c = 1;
    } else {
      state.c++;
    }
    state.done = ++state.p >= this._src.length;
  }
  isDone(state) {
    return state.done = state.p >= this._src.length;
  }
  format(state) {
    return `offset ${state.p} (${state.l}:${state.c})`;
  }
}
const defStringReader = (input) => new StringReader(input);
export {
  StringReader,
  defStringReader
};