From 35549c21bc017eb1250d7e48fddcbd6899dc8f3e Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Sun, 18 Sep 2022 01:20:17 +0200
Subject: [PATCH] A brainf**k example.

---
 lib/std/io.c3                 |  7 +++
 resources/examples/brainfk.c3 | 86 +++++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+)
 create mode 100644 resources/examples/brainfk.c3

diff --git a/lib/std/io.c3 b/lib/std/io.c3
index c1b714adb..36b4e4b36 100644
--- a/lib/std/io.c3
+++ b/lib/std/io.c3
@@ -185,6 +185,13 @@ fn String File.getline(File* file, Allocator* allocator = mem::current_allocator
 	return s;
 }
 
+fn char! File.getc(File* file)
+{
+	int c = libc::fgetc(file.file);
+	if (c == -1) return IoError.FILE_EOF!;
+	return (char)c;
+}
+
 /**
  * @param [&in] file
  * @require file.file `File must be initialized`
diff --git a/resources/examples/brainfk.c3 b/resources/examples/brainfk.c3
new file mode 100644
index 000000000..b74881cc1
--- /dev/null
+++ b/resources/examples/brainfk.c3
@@ -0,0 +1,86 @@
+// #target: macos-x64
+module brainfk;
+import std::io;
+
+const BF_MEM = 30000;
+char[BF_MEM] memory;
+
+fault InterpretError
+{
+	INTEPRET_FAILED
+}
+
+fn void! print_error(usize pos, char[] err)
+{
+	io::printfln("Error at %s: %s", pos, err);
+	return InterpretError.INTEPRET_FAILED!;
+}
+
+fn void! brainf(char[] program)
+{
+	usize sp = 0;
+	usize mem = 0;
+	while (sp < program.len)
+	{
+		char c = program[sp++];
+		switch (c)
+		{
+			case '<':
+				if (!mem) return print_error(sp, "Memory underflow");
+				mem--;
+			case '>':
+				if (mem == BF_MEM - 1) return print_error(sp, "Memory overflow");
+				mem++;
+			case '+':
+				memory[mem]++;
+			case '-':
+				memory[mem]--;
+			case '.':
+				io::putchar(memory[mem]);
+				io::stdout().flush();
+			case ',':
+				memory[mem] = io::stdin().getc()!!;
+			case '[':
+				usize indent = 1;
+				if (memory[mem]) continue;
+				usize start = sp - 1;
+				while (indent)
+				{
+					if (sp == program.len) return print_error(start, "No matching ']'");
+					switch (program[sp++])
+					{
+						case ']': indent--;
+						case '[': indent++;
+						default: break;
+					}
+				}
+			case ']':
+				if (!memory[mem]) continue;
+				usize start = sp--;
+				usize indent = 1;
+				while (indent)
+				{
+					if (!sp) return print_error(start, "No matching '['");
+					switch (program[--sp])
+					{
+						case ']': indent++;
+						case '[': indent--;
+						default: break;
+					}
+				}
+				sp++;
+			default:
+				break;
+		}
+	}
+}
+fn void! main()
+{
+	char[] program = `
+	++++[>+++++<-]>[<+++++>-]+<+[
+        >[>+>+<<-]++>>[<<+>>-]>>>[-]++>[-]+
+        >>>+[[-]++++++>>>]<<<[[<++++++++<++>>-]+<.<[>----<-]<]
+        <<[>>>>>[>>>[-]+++++++++<[>-<-]+++++++++>[-[<->-]+[<<<]]<[>+<-]>]<<-]<<-
+    ]`;
+    brainf(program)?;
+}
\ No newline at end of file