From c3389abb59f0b421fbf9798565d7240c3a4e39a5 Mon Sep 17 00:00:00 2001
From: Florian Schroedl <flo.schroedl@gmail.com>
Date: Fri, 26 Aug 2022 17:36:43 +0200
Subject: [PATCH] Add endOfStream overflow, move to parserFns, add test

---
 src_v2/parser/parser_internals.nim | 40 +++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 12 deletions(-)

diff --git a/src_v2/parser/parser_internals.nim b/src_v2/parser/parser_internals.nim
index 1e355ac..2b45f44 100644
--- a/src_v2/parser/parser_internals.nim
+++ b/src_v2/parser/parser_internals.nim
@@ -112,6 +112,31 @@ proc str*(expectedString: string): parserFnT {.inline.} =
       res = res.flatMap(ch(c))
     return res
 
+proc endOfStream*(parser: Parser): ParserResult =
+  ## Check if the following character is the end of the stream.
+  ## Errors when the end of stream was already reached.
+  let state = parser.state
+  let newIndex = state.position + 1
+
+  if newIndex == parser.state.stream.len:
+    ok(parser)
+  elif newIndex > parser.state.stream.len:
+    return err(ParserError(
+      kind: endOfStringErr,
+      expected: "endOfStream",
+      index: newIndex,
+      parser: parser,
+    ))
+  else:
+    let foundChar = state.stream[newIndex]
+    err(ParserError(
+      kind: charMismatchErr,
+      unexpected: $foundChar,
+      expected: "endOfStream",
+      index: newIndex,
+      parser: parser,
+    ))
+
 # -- Parsing API
 
 proc plus*(parserFnA: parserFnT, parserFnB: parserFnT): parserFnT {.inline.} =
@@ -197,18 +222,6 @@ proc following*(parserFns: seq[parserFnT]): parserFnT {.inline.} =
 
 # -- Parsing Aliases
 
-proc endOfStream*(parser: Parser): ParserResult =
-  let index = parser.state.position + 1
-  if index == parser.state.stream.len:
-    ok(parser)
-  else:
-    err(ParserError(
-      kind: endOfStringErr,
-      expected: &"EndOfString",
-      index: index,
-      parser: parser,
-    ))
-
 let newlineParser = choice(@[
   ch(NewLines),
   endOfStream,
@@ -264,6 +277,9 @@ when isMainModule:
     assert initParserResult("").flatMap(ch1).isStreamCompleted() == false
     assert testParser123.flatMap(str("123")).isStreamCompleted() == true
 
+    # endOfStream
+    assert testParser123.flatMap(str("123") + endOfStream).tokensToString() == "123"
+
   block testParsingApi:
     # plus, +
     assert testAbc1Parser.flatMap(str("abc") + ch('1')).tokensToString() == "abc1"