✨ map_token combinator

Author: nabeelvalley

src/parz/combinators.gleam

@@ -135,6 +135,10 @@ pub fn map(parser: Parser(a), transform) {
   }
 }
 
+pub fn map_token(parser: Parser(a), t) {
+  map(parser, fn(_) { t })
+}
+
 pub fn try_map(parser: Parser(a), transform) {
   fn(input) {
     case parser(input) {

test/combinators_test.gleam

@@ -2,9 +2,9 @@ import gleeunit/should
 import parz.{run}
 import parz/combinators.{
   as_list, between, choice, concat_str, label_error, left, many, many1, map,
-  right, separator, separator1, sequence,
+  map_token, right, separator, separator1, sequence, try_map,
 }
-import parz/parsers.{letters, str}
+import parz/parsers.{letters, regex, str}
 import parz/types.{ParserState}
 
 pub fn left_test() {
@@ -189,6 +189,54 @@ pub fn map_test() {
   |> should.be_error
 }
 
+pub fn try_map_test() {
+  let error = "No content"
+  let parser =
+    between(str("["), regex("^[A-Za-z]*"), str("]"))
+    |> try_map(fn(ok) {
+      case ok {
+        "" -> Error(error)
+        content -> Ok(Content(content))
+      }
+    })
+
+  run(parser, "[hello]")
+  |> should.be_ok
+  |> should.equal(ParserState(Content("hello"), ""))
+
+  run(parser, "[hello]x")
+  |> should.be_ok
+  |> should.equal(ParserState(Content("hello"), "x"))
+
+  run(parser, "[]x")
+  |> should.be_error
+  |> should.equal(error)
+
+  run(parser, "[hellox")
+  |> should.be_error
+}
+
+type Token {
+  Token
+}
+
+pub fn map_token_test() {
+  let parser =
+    str("hello")
+    |> map_token(Token)
+
+  run(parser, "hello")
+  |> should.be_ok
+  |> should.equal(ParserState(Token, ""))
+
+  run(parser, "hellox")
+  |> should.be_ok
+  |> should.equal(ParserState(Token, "x"))
+
+  run(parser, "xhello")
+  |> should.be_error
+}
+
 pub fn as_list_test() {
   let parser = as_list(str("x"))
 

test/simple_parser_test.gleam

@@ -1,7 +1,7 @@
 import gleeunit/should
 import parz.{run}
 import parz/combinators.{
-  choice, label_error, left, map, separator1, sequence, try_map,
+  choice, label_error, left, map, map_token, separator1, sequence, try_map,
 }
 import parz/parsers.{letters, regex, str}
 import parz/types.{ParserState}
@@ -40,9 +40,9 @@ fn parser() {
     letters()
     |> map(Identifier)
 
-  let string_kind = str("string") |> map(fn(_) { StringKind })
-  let number_kind = str("number") |> map(fn(_) { NumberKind })
-  let boolean_kind = str("boolean") |> map(fn(_) { BooleanKind })
+  let string_kind = str("string") |> map_token(StringKind)
+  let number_kind = str("number") |> map_token(NumberKind)
+  let boolean_kind = str("boolean") |> map_token(BooleanKind)
 
   let kind = choice([string_kind, number_kind, boolean_kind])
   let node =