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/brainfuck.cr | 14 ++++++++++++++
 src/brainfuck/parser.cr    | 30 +++++++++++++++++++++++++++++-
 src/brainfuck/program.cr   | 14 ++++++++++++++
 3 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 src/brainfuck/program.cr

(limited to 'src/brainfuck')

diff --git a/src/brainfuck/brainfuck.cr b/src/brainfuck/brainfuck.cr
index 78c504c..b75ad1c 100644
--- a/src/brainfuck/brainfuck.cr
+++ b/src/brainfuck/brainfuck.cr
@@ -13,5 +13,19 @@ module Brainfuck
     LoopStart
     LoopEnd
   end
+
+  def self.opcode_from_char(c : Char) : Opcode?
+    case c
+    when '>' then Opcode::PtrRight
+    when '<' then Opcode::PtrLeft
+    when '+' then Opcode::Inc
+    when '-' then Opcode::Dec
+    when '.' then Opcode::Out
+    when ',' then Opcode::In
+    when '[' then Opcode::LoopStart
+    when ']' then Opcode::LoopEnd
+    else nil
+    end
+  end
 end
 
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
 
diff --git a/src/brainfuck/program.cr b/src/brainfuck/program.cr
new file mode 100644
index 0000000..cf4a097
--- /dev/null
+++ b/src/brainfuck/program.cr
@@ -0,0 +1,14 @@
+require "./parser.cr"
+
+class Brainfuck::Program
+  def initialize(@parser : Brainfuck::Parser)
+  end
+
+  def interpret
+    puts @parser.parse
+  end
+
+  def compile
+  end
+end
+
-- 
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