@thi.ng/parse/prims/string.js

Purely functional parser combinators & AST generation for generic inputs

const string = (str, id = "string") => (ctx) => {
  if (ctx.done) return false;
  const scope = ctx.start(id);
  const state = scope.state;
  const reader = ctx.reader;
  for (let i = 0, n = str.length; i < n; i++) {
    if (state.done) return false;
    if (reader.read(state) !== str[i]) {
      return ctx.discard();
    }
    reader.next(state);
  }
  scope.result = str;
  return ctx.end();
};
const stringD = (str) => (ctx) => {
  if (ctx.done) return false;
  const state = ctx.state.copy();
  const reader = ctx.reader;
  for (let i = 0, n = str.length; i < n; i++) {
    if (state.done) return false;
    if (reader.read(state) !== str[i]) {
      return false;
    }
    reader.next(state);
  }
  ctx.state = state;
  return true;
};
const stringOf = (pred, id = "string", reduce = (x) => x.join("")) => (ctx) => {
  const state = ctx.state.copy();
  const reader = ctx.reader;
  let acc = [];
  while (!state.done) {
    const r = reader.read(state);
    if (!pred(r)) break;
    acc.push(r);
    reader.next(state);
  }
  return ctx.addChild(id, reduce(acc), state);
};
export {
  string,
  stringD,
  stringOf
};