2 files changed, 82 insertions, 1 deletions
diff --git a/src/parser/index.ts b/src/parser/index.ts
new file mode 100644
index 0000000..f522214
--- /dev/null
+++ b/src/parser/index.ts
@@ -0,0 +1,81 @@
+import { constant, pipe } from 'fp-ts/function'
+import { chain, orElse, right } from 'fp-ts/lib/Either'
+import {
+  delimited,
+  many1,
+  mapTo,
+  optional,
+  or,
+  Parser,
+  ParserResult,
+  symbol,
+  tuple3,
+} from './utils'
+import { Expr } from '../types'
+
+export const start = mapTo(symbol('^'), constant({ tag: 'Start' } as Expr))
+export const end = mapTo(symbol('$'), constant({ tag: 'End' } as Expr))
+export const anyItem = mapTo(symbol('.'), constant({ tag: 'AnyItem' } as Expr))
+export const nextItem = mapTo(
+  symbol(','),
+  constant({ tag: 'NextItem' } as Expr)
+)
+export const anyString = mapTo(
+  symbol('\\s'),
+  constant({ tag: 'AnyString' } as Expr)
+)
+export const anyNumber = mapTo(
+  symbol('\\n'),
+  constant({ tag: 'AnyNumber' } as Expr)
+)
+export const anyBool = mapTo(
+  symbol('\\b'),
+  constant({ tag: 'AnyBool' } as Expr)
+)
+export const truthy = mapTo(symbol('\\T'), constant({ tag: 'Truthy' } as Expr))
+export const falsey = mapTo(symbol('\\F'), constant({ tag: 'Falsey' } as Expr))
+
+export const wrapQuantifiers: (e: ParserResult<Expr>) => ParserResult<Expr> =
+  chain(([expr, input]) =>
+    pipe(
+      input,
+      or([
+        mapTo(symbol('*'), (_) => ({ tag: 'ZeroOrMore', expr } as Expr)),
+        mapTo(symbol('+'), (_) => ({ tag: 'OneOrMore', expr } as Expr)),
+        mapTo(symbol('?'), (_) => ({ tag: 'Optional', expr } as Expr)),
+      ]),
+      orElse(() => right([expr, input]))
+    )
+  )
+
+export const expressionP: Parser<Expr> = (input: string) =>
+  pipe(
+    input,
+    or([
+      mapTo(
+        delimited(symbol('('), many1(expressionP), symbol(')')),
+        (exprs) => ({ tag: 'Group', exprs } as Expr)
+      ),
+      nextItem,
+      anyItem,
+      anyString,
+      anyNumber,
+      anyBool,
+      truthy,
+      falsey,
+    ]),
+    wrapQuantifiers
+  )
+
+export const parser = tuple3(optional(start), many1(expressionP), optional(end))
+
+/*
+
+{3,6} => 3 to 6 instances
+(> 5) => number greater than
+(< 5) => number less than
+[name x] => apply x on property `name`
+| => or
+/x/ => match regular expression (string values in list)
+
+*/
diff --git a/src/parser.ts b/src/parser/utils.ts
index a7d6528..00b50f8 100644
--- a/src/parser.ts
+++ b/src/parser/utils.ts
@@ -11,7 +11,7 @@ import {
 } from 'fp-ts/Either'
 import { none, some, Option } from 'fp-ts/Option'
 import { mapFst, mapSnd, snd } from 'fp-ts/Tuple'
-import { eq } from './utils'
+import { eq } from '../utils'
 
 export type char = string