From 4dd4e596ae6e5da84f2ce4296cbf9c030efe69bb Mon Sep 17 00:00:00 2001
From: Matthew Hall <hallmatthew314@gmail.com>
Date: Fri, 2 Sep 2022 21:03:42 +1200
Subject: Can read code from STDIN, can parse brainfuck

---
 src/brainfuck/parser.cr | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

(limited to 'src/brainfuck/parser.cr')

diff --git a/src/brainfuck/parser.cr b/src/brainfuck/parser.cr
index b937f73..df381e3 100644
--- a/src/brainfuck/parser.cr
+++ b/src/brainfuck/parser.cr
@@ -1,5 +1,33 @@
+require "./brainfuck.cr"
+require "../util.cr"
+
 class Brainfuck::Parser
-  def initialize()
+  def initialize(code_io : IO)
+    @raw_code = code_io.gets_to_end
+    code_io.close # just in case
+  end
+
+  def parse
+    loop_depth = 0
+    code = [] of Opcode
+    @raw_code.chars.each do |c|
+      op = Brainfuck.opcode_from_char(c)
+      unless op.nil?
+        if loop_depth == 0 && op == Opcode::LoopEnd
+          raise Util::ParserError.new("Missing loop entrance(s)")
+        end
+
+        loop_depth -= 1 if op == Opcode::LoopEnd
+        loop_depth += 1 if op == Opcode::LoopStart
+        code << op
+      end
+    end
+
+    unless loop_depth == 0
+      raise Util::ParserError.new("Missing loop exit(s)")
+    end
+
+    return code
   end
 end
 
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