From 8323c9f6a1b52792979b7e4a7afc6f1cb5ff9add Mon Sep 17 00:00:00 2001
From: rowan <rowan@kitsu.cafe>
Date: Wed, 16 Apr 2025 14:53:46 -0500
Subject: [PATCH] split up parser.js

---
 .gitmodules       |   3 +
 jsconfig.json     |  16 ++
 src/char.js       |  36 ++++
 src/combinator.js |  34 ++++
 src/cond.js       |  18 ++
 src/const.js      |   6 +
 src/fn.js         |  99 +++++++++++
 src/index.js      |   6 +-
 src/iter.js       | 406 ++++++++++++++++++++++++++++++++++++++++++++++
 src/parser.js     | 126 --------------
 src/seq.js        |  55 +++++++
 src/state.js      |  23 +++
 vendor/izuna      |   1 +
 vendor/kojima     |   2 +-
 14 files changed, 703 insertions(+), 128 deletions(-)
 create mode 100644 jsconfig.json
 create mode 100644 src/char.js
 create mode 100644 src/combinator.js
 create mode 100644 src/cond.js
 create mode 100644 src/const.js
 create mode 100644 src/fn.js
 create mode 100644 src/iter.js
 delete mode 100644 src/parser.js
 create mode 100644 src/seq.js
 create mode 100644 src/state.js
 create mode 160000 vendor/izuna

diff --git a/.gitmodules b/.gitmodules
index bcab54b..fbf17c0 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "vendor/kojima"]
 	path = vendor/kojima
 	url = https://git.kitsu.cafe/rowan/kojima.git
+[submodule "vendor/izuna"]
+	path = vendor/izuna
+	url = https://git.kitsu.cafe/rowan/izuna.git
diff --git a/jsconfig.json b/jsconfig.json
new file mode 100644
index 0000000..e74eccc
--- /dev/null
+++ b/jsconfig.json
@@ -0,0 +1,16 @@
+{
+  "compilerOptions": {
+    "strict": true,
+    "module": "es2020",
+    "target": "es6",
+    "lib": ["es2022", "dom"],
+    "checkJs": false,
+    "paths": {
+      "/*": ["./*"]
+    }
+  },
+  "exclude": [
+    "node_modules"
+  ]
+}
+
diff --git a/src/char.js b/src/char.js
new file mode 100644
index 0000000..50b23fc
--- /dev/null
+++ b/src/char.js
@@ -0,0 +1,36 @@
+import { State } from './state.js'
+import { anyOf } from './combinator.js'
+import { Alpha, Alphanumeric, Digits, LowerAlpha, UpperAlpha } from './const.js'
+import { fail, join, mapStr, next, succeed } from './fn.js'
+import { map, seq } from './seq.js'
+import { curry } from '../vendor/izuna/src/curry.js'
+
+/** @import { ParserState } from './state.js' */
+
+export const char = curry(
+  /**
+   * @param {string} ch
+   * @param {ParserState} state
+   */
+  (ch, state) => (
+    next(state) === ch ? succeed(ch, state) : fail(`could not parse ${ch} `, state)
+  ))
+
+export const str = curry(
+  /**
+   * @param {string} str
+   * @param {State} state
+   */
+  (str, state) => (
+    map(
+      join(''),
+      seq(...mapStr(char, str))
+    )(state)
+  ))
+
+export const digit = anyOf(Digits)
+export const lowerAlpha = anyOf(LowerAlpha)
+export const upperAlpha = anyOf(UpperAlpha)
+export const alpha = anyOf(Alpha)
+export const alphanumeric = anyOf(Alphanumeric)
+
diff --git a/src/combinator.js b/src/combinator.js
new file mode 100644
index 0000000..25b665d
--- /dev/null
+++ b/src/combinator.js
@@ -0,0 +1,34 @@
+import { char } from './char.js'
+import { fail, fork, mapStr } from './fn.js'
+import { curry } from '../vendor/izuna/src/curry.js'
+
+/** @import { ParserState } from './state.js' */
+
+/**
+ * @param {...any} parsers
+ */
+export const any = (...parsers) =>
+  /**
+   * @param {ParserState} state
+   */
+  state => {
+    for (const parser of parsers) {
+      const [original, clone] = fork(state)
+      const result = parser(clone)
+      if (result.isOk) {
+        return result
+      }
+    }
+
+    return fail('no matching parsers', state)
+  }
+
+export const anyOf = curry(
+  /**
+    * @param {string} str
+    * @param {ParserState} state
+    */
+  (str, state) => (
+    any(...mapStr(char, str))(state)
+  ))
+
diff --git a/src/cond.js b/src/cond.js
new file mode 100644
index 0000000..9b32d8d
--- /dev/null
+++ b/src/cond.js
@@ -0,0 +1,18 @@
+import { ParseError } from './state.js'
+import { curry } from '../vendor/izuna/src/index.js'
+import { fork, succeed } from './fn.js'
+
+/** @import { Result } from '../vendor/kojima/src/index.js' */
+/** @import { ParserState } from './state.js' */
+
+export const maybe = curry(
+  /**
+    * @param {(...args: any[]) => Result<ParserState, ParseError>} parser
+    * @param {ParserState} state
+    */
+  (parser, state) => {
+    const [original, clone] = fork(state)
+    const result = parser(clone)
+    return result.isOk() ? result : succeed([], original)
+  })
+
diff --git a/src/const.js b/src/const.js
new file mode 100644
index 0000000..f51d393
--- /dev/null
+++ b/src/const.js
@@ -0,0 +1,6 @@
+export const LowerAlpha = 'abcdefghijklmnopqrstuvwxyz'
+export const UpperAlpha = LowerAlpha.toUpperCase()
+export const Alpha = LowerAlpha + UpperAlpha
+export const Digits = '1234567890'
+export const Alphanumeric = Alpha + Digits
+
diff --git a/src/fn.js b/src/fn.js
new file mode 100644
index 0000000..82dbc88
--- /dev/null
+++ b/src/fn.js
@@ -0,0 +1,99 @@
+import { ParseError } from './state.js'
+import { Iter } from './iter.js'
+import { err, ok } from '../vendor/kojima/src/index.js'
+import { curry } from '/vendor/izuna/src/index.js'
+
+/** @import { ParserState } from './state.js'* /
+
+/**
+ * @param {...any} values
+ */
+export const Tuple = (...values) => Object.freeze(values)
+
+/**
+ * @template T
+ * @param {Iterator<T> | Iterable<T>} iterable
+ * @param {number} [n=2]
+ */
+function tee(iterable, n = 2) {
+  const iterator = Iter.from(iterable)
+
+  /**
+   * @param {{ next: any, value: T }} current 
+   */
+  function* gen(current) {
+    while (true) {
+      if (!current.next) {
+        const { done, value } = iterator.next()
+        if (done) return
+        current.next = { value }
+      }
+
+      current = current.next
+      yield current.value
+    }
+  }
+
+  return Array(n).fill({}).map(gen)
+}
+
+/**
+ * @param {import('./state.js').ParserState} state
+ */
+export const fork = ([tokens, state]) => {
+  const [a, b] = tee(state)
+  return Tuple(
+    Tuple(tokens.slice(), a),
+    Tuple(tokens.slice(), b),
+  )
+}
+
+/**
+ * @template T
+ * @param {T | T[]} v
+ * @param {ParserState} state
+ */
+export const succeed = (v, [x, y]) => ok(Tuple(x.concat(v), y))
+
+/**
+ * @param {string} msg
+ * @param {ParserState} state
+ * @param {Error} [e]
+ */
+export const fail = (msg, state, e = undefined) => err(new ParseError(msg, state, e))
+
+/**
+ * @template T
+ * @param {number & keyof T} n
+ * @param {T[]} iter
+ */
+export const nth = (n, iter) => iter[n]
+
+/**
+ * @param {ParserState} state
+ */
+export const next = state => state[1].next().value
+
+/**
+ * @template T
+ * @param {T[]} a
+ * @param {T[]} b
+ */
+export const diff = (a, b) => b.slice(-Math.max(0, b.length - a.length))
+
+export const join = curry(
+  /**
+    * @param {string} delim
+    * @param {string[]} val
+    */
+  (delim, val) => val.join(delim)
+)
+
+export const mapStr = curry(
+  /**
+    * @param {(...args: any[]) => any} fn
+    * @param {string} str
+    */
+  (fn, str) => Array.from(str).map(v => fn(v))
+)
+
diff --git a/src/index.js b/src/index.js
index 7236d68..a797e01 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,2 +1,6 @@
-export * from './parser.js'
+export * from './char.js'
+export * from './combinator.js'
+export * from './cond.js'
+export * from './seq.js'
+export * from './state.js'
 
diff --git a/src/iter.js b/src/iter.js
new file mode 100644
index 0000000..25e5e05
--- /dev/null
+++ b/src/iter.js
@@ -0,0 +1,406 @@
+/**
+ * @template T
+ * @implements Iterator<T>
+ * @implements Iterable<T>
+ */
+export class Iter {
+  _iterator
+
+  /**
+   * @param {Iterator<T>} iterator 
+   */
+  constructor(iterator) {
+    this._iterator = iterator
+  }
+
+  /**
+   * @template T
+   * @param {any} value 
+   * @returns {value is Iterable<T>}
+   */
+  static _isIterable(value) {
+    return Object.hasOwn(value, Symbol.iterator)
+      && typeof value[Symbol.iterator] === 'function'
+  }
+
+  /**
+   * @template T
+   * @param {T} value 
+   */
+  static from(value) {
+    if (value instanceof Iter) {
+      return value
+    }
+
+    if (Iter._isIterable(value)) {
+      const iterator = value[Symbol.iterator]()
+
+      if (iterator instanceof Iter) {
+        return iterator
+      }
+
+      return new Iter(iterator)
+    }
+
+    throw new TypeError('object is not an iterator')
+  }
+
+  /**
+   * @param {any} [value]
+   */
+  next(value) {
+    return this._iterator.next(value)
+  }
+
+  /**
+   * @param {any} [value]
+   */
+  return(value) {
+    // @ts-ignore
+    return this._iterator.return(value)
+  }
+
+  /**
+   * @param {any} err
+   */
+  throw(err) {
+    // @ts-ignore
+    return this._iterator.throw(err)
+  }
+
+  /**
+   * @param {number} limit
+   */
+  drop(limit) {
+    return new DropIter(this, limit)
+  }
+
+  /**
+   * @param {(value: T, index: number) => boolean} callbackFn
+   */
+  every(callbackFn) {
+    let next = this.next()
+    let index = 0
+    let result = true
+
+    while (!next.done) {
+      if (!callbackFn(next.value, index)) {
+        result = false
+        break
+      }
+
+      next = this.next()
+      index += 1
+    }
+
+    this.return()
+    return result
+  }
+
+  /**
+   * @param {(value: T, index: number) => boolean} callbackFn
+   */
+  filter(callbackFn) {
+    return new FilterIter(this, callbackFn)
+  }
+
+  /**
+   * @param {(value: T, index: number) => boolean} callbackFn
+   */
+  find(callbackFn) {
+    let next = this.next()
+    let index = 0
+
+    while (!next.done) {
+      if (callbackFn(next.value, index)) {
+        this.return()
+        return next.value
+      }
+
+      next = this.next()
+      index += 1
+    }
+  }
+
+  /**
+   * @param {<U>(value: T, index: number) => U} callbackFn
+   */
+  flatMap(callbackFn) {
+    return new FlatMapIter(this, callbackFn)
+  }
+
+  /**
+   * @param {(value: T, index: number) => void} callbackFn
+   */
+  forEach(callbackFn) {
+    let next = this.next()
+    let index = 0
+
+    while (!next.done) {
+      callbackFn(next.value, index)
+      next = this.next()
+      index += 1
+    }
+  }
+
+  /**
+   * @param {<U>(value: T, index: number) => U} callbackFn
+   */
+  map(callbackFn) {
+    return new MapIter(this, callbackFn)
+  }
+
+  /**
+   * @template U
+   * @param {(accumulator: U, value: T, index: number) => U} callbackFn
+   * @param {U} init 
+   */
+  reduce(callbackFn, init) {
+    let next = this.next()
+    let index = 0
+    let acc = init
+
+    while (!next.done) {
+      acc = callbackFn(acc, next.value, index)
+
+      next = this.next()
+      index += 1
+    }
+
+    this.return()
+    return acc
+  }
+
+  /**
+   * @param {(value: T, index: number) => boolean} callbackFn
+   */
+  some(callbackFn) {
+    let next = this.next()
+    let index = 0
+    let result = false
+
+    while (!next.done) {
+      if (callbackFn(next.value, index)) {
+        result = true
+        break
+      }
+
+      next = this.next()
+      index += 1
+    }
+
+    this.return()
+    return result
+  }
+
+  /**
+   * @param {number} limit
+   */
+  take(limit) {
+    return new TakeIter(this, limit)
+  }
+
+  /*
+   * @returns {T[]}
+   */
+  toArray() {
+    /** @type {T[]} */
+    const result = []
+
+    for (const item of this) {
+      result.push(item)
+    }
+
+    return result
+  }
+
+  *[Symbol.iterator]() {
+    return this
+  }
+}
+
+/**
+ * @template T
+ * @extends Iter<T>
+ */
+class DropIter extends Iter {
+  _limit
+
+  /**
+   * @param {Iterator<T>} iterator
+   * @param {number} limit
+   */
+  constructor(iterator, limit) {
+    super(iterator)
+    this._limit = limit
+  }
+
+  /**
+   * @param {any} value
+   */
+  next(value) {
+    for (let i = this._limit; i > 0; i--) {
+      const next = super.next(value)
+
+      if (next.done) {
+        return next
+      }
+    }
+
+    return super.next(value)
+  }
+}
+
+/**
+ * @template T
+ * @extends Iter<T>
+ */
+class FilterIter extends Iter {
+  _filter
+  _index = 0
+
+  /**
+   * @param {Iterator<T>} iterator
+   * @param {(value: T, index: number) => boolean} callbackFn
+   */
+  constructor(iterator, callbackFn) {
+    super(iterator)
+    this._filter = callbackFn
+  }
+
+  /**
+   * @param {any} [value]
+   * @returns {IteratorResult<T>}
+   */
+  next(value) {
+    let next = super.next(value)
+
+    while (!next.done && !this._filter(next.value, this._index)) {
+      next = super.next(value)
+      this._index += 1
+    }
+
+    return next
+  }
+}
+
+/**
+ * @template T
+ * @extends Iter<T>
+ */
+class FlatMapIter extends Iter {
+  _flatMap
+  _index = 0
+
+  /** @type {Iterator<T> | undefined} */
+  _inner = undefined
+
+  /**
+   * @param {Iterator<T>} iterator
+   * @param {<U>(value: T, index: number) => Iterator<U> | Iterable<U>} callbackFn 
+   */
+  constructor(iterator, callbackFn) {
+    super(iterator)
+    this._flatMap = callbackFn
+  }
+
+  /**
+   * @param {any} value
+   * @returns {IteratorResult<T>}
+   */
+  next(value) {
+    if (this._inner) {
+      const innerResult = this._inner.next(value)
+
+      if (!innerResult.done) {
+        this._index += 1
+        return { value: innerResult.value, done: false }
+      }
+
+      this._inner = undefined
+    }
+
+    const outerResult = super.next(value)
+    if (outerResult.done) {
+      return { value: undefined, done: true }
+    }
+
+    const nextIterable = this._flatMap(outerResult.value, this._index || 0)
+    if (Iter._isIterable(nextIterable)) {
+      this._inner = Iter.from(nextIterable)
+      return this.next(value)
+    } else {
+      throw new TypeError('value is not an iterator')
+    }
+  }
+}
+
+/**
+ * @template T
+ * @extends Iter<T>
+ */
+class MapIter extends Iter {
+  _map
+  _index = 0
+
+  /**
+   * @param {Iterator<T>} iterator 
+   * @param {<U>(value: T, index: number) => U} callbackFn 
+   */
+  constructor(iterator, callbackFn) {
+    super(iterator)
+    this._map = callbackFn
+  }
+
+  /** @param {any} value */
+  next(value) {
+    let next = super.next(value)
+
+    if (next.done) {
+      return next
+    }
+
+    const result = {
+      done: false,
+      value: this._map(next.value, this._index)
+    }
+
+    this._index += 1
+    return result
+  }
+}
+
+
+/**
+ * @template T
+ * @extends Iter<T>
+ */
+class TakeIter extends Iter {
+  _limit
+
+  /**
+   * @param {Iterator<T>} iterator 
+   * @param {number} limit
+   */
+  constructor(iterator, limit) {
+    super(iterator)
+    this._limit = limit
+  }
+
+  /**
+   * @param {any} value
+   * @returns {IteratorResult<T>}
+   */
+  next(value) {
+    if (this._limit > 0) {
+      const next = super.next(value)
+      if (!next.done) {
+        this._limit -= 1
+      }
+      return next
+    }
+
+    return { value: undefined, done: true }
+  }
+}
+
diff --git a/src/parser.js b/src/parser.js
deleted file mode 100644
index eca5eb8..0000000
--- a/src/parser.js
+++ /dev/null
@@ -1,126 +0,0 @@
-import { Ok, Err, curry } from '../vendor/kojima/src/index.js'
-
-export class ParseError extends Error {
-  constructor(message, state, source) {
-    super(message)
-    this.state = state
-    this.source = source
-  }
-}
-
-const Tuple = (...values) => Object.freeze(values)
-const State = value => Tuple([], Iterator.from(value))
-
-const LowerAlpha = 'abcdefghijklmnopqrstuvwxyz'
-const UpperAlpha = LowerAlpha.toUpperCase()
-const Alpha = LowerAlpha + UpperAlpha
-const Digits = '1234567890'
-const Alphanumeric = Alpha + Digits
-
-
-const tee = (iterator, n = 2) => {
-  iterator = Iterator.from(iterator)
-
-  function* gen(current) {
-    while (true) {
-      if (!current.next) {
-        const { done, value } = iterator.next()
-        if (done) { return }
-        current.next = { value }
-      }
-      current = current.next
-      yield current.value
-    }
-  }
-
-  return Array(n).fill({}).map(gen)
-}
-
-const fork = ([tokens, state]) => {
-  const [a, b] = tee(state)
-  return Tuple(
-    Tuple(tokens.slice(), a),
-    Tuple(tokens.slice(), b),
-  )
-}
-
-export const succeed = (v, [x, y]) => Ok(Tuple(x.concat(v), y))
-export const fail = (msg, state, err = undefined) => Err(new ParseError(msg, state, err))
-const nth = (n, iter) => iter[n]
-const next = state => nth(1, state).next().value
-const diff = (a, b) => b.slice(-Math.max(0, b.length - a.length))
-const join = curry((delim, val) => val.join(delim))
-const mapStr = curry((fn, str) => Array.from(str).map(v => fn(v)))
-
-export const any = (...parsers) => state => {
-  for (const parser of parsers) {
-    const [original, clone] = fork(state)
-    const result = parser(clone)
-    if (result.isOk) {
-      return result
-    }
-  }
-
-  return fail('no matching parsers', state)
-}
-
-export const anyOf = curry((str, state) => (
-  any(...mapStr(char, str))(state)
-))
-
-export const seq = (...parsers) => state => {
-  let acc = Ok(state)
-
-  for (const parser of parsers) {
-    if (acc.isOk) {
-      acc = acc.bind(parser)
-    } else {
-      break
-    }
-  }
-
-  return acc
-}
-
-export const map = curry((fn, parser, state) => {
-  return parser(state).bind(result => {
-    try {
-      const parsed = diff(state[0], result[0])
-      const backtrack = Tuple(state[0], result[1])
-      return succeed(fn(parsed), backtrack)
-    } catch (e) {
-      return fail('failed to map', state, e)
-    }
-  })
-})
-
-export const char = curry((ch, state) => (
-  next(state) === ch ? succeed(ch, state) : fail(`could not parse ${ch} `, state)
-))
-
-export const anyChar = state => {
-  const ch = next(state)
-  return !!ch ? succeed(ch, state) : fail(`could not parse ${ch}`, state)
-}
-
-export const str = curry((str, state) => (
-  map(
-    join(''),
-    seq(...mapStr(char, str))
-  )(state)
-))
-
-export const digit = anyOf(Digits)
-export const lowerAlpha = anyOf(LowerAlpha)
-export const upperAlpha = anyOf(UpperAlpha)
-export const alpha = anyOf(Alpha)
-export const alphanumeric = anyOf(Alphanumeric)
-
-export const maybe = curry((parser, state) => {
-  const [original, clone] = fork(state)
-  const result = parser(clone)
-  return result.isOk ? result : succeed([], original)
-})
-
-export const parse = curry((parser, input) => parser(State(input)))
-
diff --git a/src/seq.js b/src/seq.js
new file mode 100644
index 0000000..1a8c998
--- /dev/null
+++ b/src/seq.js
@@ -0,0 +1,55 @@
+import { diff, fail, succeed, Tuple } from './fn.js'
+import { ok } from '../vendor/kojima/src/index.js'
+import { curry } from '../vendor/izuna/src/curry.js'
+
+/** @import { ParseError, ParserState } from './state.js' */
+/** @import { Result } from '../vendor/kojima/src/index.js' */
+
+/**
+ * @typedef {(value: any) => Result<ParserState, ParseError>} Parser
+ */
+
+/**
+ * @param {...Parser} parsers
+ */
+export const seq = (...parsers) =>
+  /** @param {ParserState} state */
+  state => {
+    let acc = ok(state)
+
+    for (const parser of parsers) {
+      if (acc.isOk()) {
+        acc = acc.bind(parser)
+      } else {
+        break
+      }
+    }
+
+    return acc
+  }
+
+export const map = curry(
+  /** 
+   * @param {(...args: any[]) => any} fn
+   * @param {Parser} parser
+   * @param {ParserState} state
+   */
+  (fn, parser, state) => {
+    return parser(state).map(result => {
+      try {
+        /** @type {Result<ParserState, ParseError>} */
+        const parsed = result.chain(otherState =>
+          fn(diff(state[0], otherState[0]))
+        )
+
+        const backtrack = result.chain(otherState =>
+          Tuple(state[0], otherState[1])
+        )
+
+        return succeed(parsed, backtrack)
+      } catch (e) {
+        return fail('failed to map', state, e)
+      }
+    })
+  })
+
diff --git a/src/state.js b/src/state.js
new file mode 100644
index 0000000..071fcbe
--- /dev/null
+++ b/src/state.js
@@ -0,0 +1,23 @@
+import { Iter } from './iter.js'
+/**
+ * @typedef {Readonly<[any[], Iterator<any>]>} ParserState
+ */
+
+export class ParseError extends Error {
+  /**
+   * @param {string} message
+   * @param {ParserState} state
+   * @param {Error} [cause]
+   */
+  constructor(message, state, cause) {
+    super(message, { cause })
+    this.state = state
+  }
+}
+
+/**
+ * @param {any} value
+ * @returns {ParserState}
+ */
+export const State = value => Object.freeze([[], Iter.from(value)])
+
diff --git a/vendor/izuna b/vendor/izuna
new file mode 160000
index 0000000..aa70427
--- /dev/null
+++ b/vendor/izuna
@@ -0,0 +1 @@
+Subproject commit aa70427c8c349bbfe4576cba878f5b44859007d4
diff --git a/vendor/kojima b/vendor/kojima
index 1402219..d661524 160000
--- a/vendor/kojima
+++ b/vendor/kojima
@@ -1 +1 @@
-Subproject commit 1402219aad22f55c39ac448bff372474a17f5c00
+Subproject commit d6615248572d2e5c16661d8aab0650ae28aeb6c2