From 9e29dd5678d463426d224ad50014a37b04ff34cc Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Mon, 4 Oct 2021 23:47:22 +0200
Subject: Implemented Funge-98 IO procedures

---
 src/defaultIO.nim   | 40 ++++++++++++++++++++++++++++++++++++++++
 tests/defaultIO.nim | 25 +++++++++++++++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 src/defaultIO.nim
 create mode 100644 tests/defaultIO.nim

diff --git a/src/defaultIO.nim b/src/defaultIO.nim
new file mode 100644
index 0000000..52bcb83
--- /dev/null
+++ b/src/defaultIO.nim
@@ -0,0 +1,40 @@
+import strformat
+
+## We keep the last input char to handle a pain point in the funge-98 spec :
+## when reading from the decimal input you need to read until you encounter a
+## non numeric char, but not drop it
+var defaultInputLastChar: ref int
+
+var stdIoUnbuffered = false
+
+proc defaultCharacterInput*(): int =
+  if defaultInputLastChar != nil:
+    result = defaultInputLastChar[]
+    defaultInputLastChar = nil
+    return result
+  if not stdIoUnbuffered:
+    setStdIoUnbuffered()
+    stdIoUnbuffered = true
+  return stdin.readChar().int()
+
+proc defaultDecimalInput*(): int =
+  while true: # First we need to find the next numeric char
+    let c = defaultCharacterInput()
+    if c >= int('0') and c <= int('9'):
+      result = c - int('0')
+      break
+  while true: # then we read until we encounter a non numeric char
+    let c = defaultCharacterInput()
+    if c >= int('0') and c <= int('9'):
+      result = result * 10 + c - int('0')
+    else:
+      new(defaultInputLastChar)
+      defaultInputLastChar[] = c
+      break
+  return result
+
+proc defaultCharacterOutput*(v: int) =
+  discard stdout.writeChars(@[v.char()], 0, 1)
+
+proc defaultDecimalOutput*(v: int) =
+  stdout.write(&"{v}")
diff --git a/tests/defaultIO.nim b/tests/defaultIO.nim
new file mode 100644
index 0000000..2de2330
--- /dev/null
+++ b/tests/defaultIO.nim
@@ -0,0 +1,25 @@
+discard """
+  input: "ab1234cd12f"
+  output: '''
+[Suite] defaultIO
+gh789
+  '''
+"""
+
+import unittest
+
+include ../src/defaultIO
+
+suite "defaultIO":
+  test "defaultCharacterInput":
+    check defaultCharacterInput() == 'a'.int
+    check defaultCharacterInput() == 'b'.int
+    check defaultCharacterInput() == '1'.int
+  test "defaultDecimalInput":
+    check defaultDecimalInput() == 234
+    check defaultCharacterInput() == 'c'.int
+  test "defaultCharacterOutput":
+    defaultCharacterOutput('g'.int)
+    defaultCharacterOutput('h'.int)
+  test "defaultDecimalOutput":
+    defaultDecimalOutput(789)
-- 
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