From 952256ae8bf5514a246db8f33bef207f5747b138 Mon Sep 17 00:00:00 2001
From: Akshay Nair <phenax5@gmail.com>
Date: Fri, 11 Aug 2023 17:13:57 +0530
Subject: feat: adds parser for literal numbers

---
 src/parser.ts            | 11 +++++++++++
 src/utils/parser-comb.ts |  8 ++++++++
 2 files changed, 19 insertions(+)

(limited to 'src')

diff --git a/src/parser.ts b/src/parser.ts
index 1c5c08f..8230825 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -1,11 +1,14 @@
 import { Enum, constructors, match } from './utils/adt'
 import * as P from './utils/parser-comb'
 
+type Unit = '' | 's' | 'ms'
+
 export type Expr = Enum<{
   Call: { name: string; args: Expr[] }
   Identifier: string
   VarIdentifier: string
   LiteralString: string
+  LiteralNumber: { value: number, unit: Unit }
 }>
 
 export const Expr = constructors<Expr>()
@@ -41,9 +44,17 @@ const stringLiteralParser: P.Parser<Expr> = P.map(
   Expr.LiteralString
 )
 
+const numberParser = P.regex(/^[-+]?((\d*\.\d+)|\d+)/)
+
+const numberExprParser: P.Parser<Expr> = P.map(
+  P.zip2(numberParser, P.optional(P.regex(/^(s|ms)/i))),
+  ([value, unit]) => Expr.LiteralNumber({ value: Number(value), unit: (unit ?? '') as Unit }),
+)
+
 const exprParser: P.Parser<Expr> = P.or([
   stringLiteralParser,
   varIdentifierExprParser,
+  numberExprParser,
   callExprParser,
   identifierExprParser,
 ])
diff --git a/src/utils/parser-comb.ts b/src/utils/parser-comb.ts
index e0665f6..f682068 100644
--- a/src/utils/parser-comb.ts
+++ b/src/utils/parser-comb.ts
@@ -73,3 +73,11 @@ export const sepBy = <A>(parser: Parser<A>, sepP: Parser<any>): Parser<Array<A>>
     Err: _ => Result.Ok({ value: [], input: originalInput }),
   })
 
+export const optional = <A>(parser: Parser<A>): Parser<undefined | A> => input => {
+  const result = parser(input)
+  return match(result, {
+    Ok: _ => result,
+    Err: _ => Result.Ok({ value: undefined, input })
+  })
+}
+
-- 
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