5 files changed, 87 insertions, 7 deletions
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
+
diff --git a/src/flint.cr b/src/flint.cr
index 39d8363..1c67cc9 100644
--- a/src/flint.cr
+++ b/src/flint.cr
@@ -2,6 +2,7 @@
 
 require "option_parser"
 
+require "./util.cr"
 require "./brainfuck/*"
 require "./brainfuck/parser.cr"
 
@@ -13,6 +14,7 @@ module Flint
     chosen_language = nil
     memory_size = nil
     source_file = nil
+    read_stdin = false
 
     parser = OptionParser.new do |parser|
       parser.banner = "Basic usage: flint [LANGUAGE] [OPTIONS] [FILE]"
@@ -33,6 +35,9 @@ module Flint
       parser.on("-c", "--compile", "produce a binary or different source code file instead of interpeting the code, overrides an explicit '-i' or '--intepret' flag") do
         execution_mode = :compile
       end
+      parser.on("--stdin", "read source code from STDIN instead of a file") do
+        read_stdin = true
+      end
 
       parser.unknown_args do |_args|
         source_file = _args[0] unless _args.empty?
@@ -47,17 +52,31 @@ module Flint
       exit(1)
     end
 
-    if source_file.nil?
+    if read_stdin
+      source_io = STDIN
+    elsif source_file
+      # compilier complains without the not_nil!
+      source_io = File.new(source_file.not_nil!)
+    else
       puts "ERROR: No source file chosen"
       puts parser
+      puts source_file.nil?
+      puts (!read_stdin)
       exit(1)
     end
 
-    # temporary
-    puts execution_mode
-    puts chosen_language
-    puts memory_size
-    puts source_file
+    if chosen_language == :brainfuck
+      bf_parser = Brainfuck::Parser.new(source_io)
+      program = Brainfuck::Program.new(bf_parser)
+    end
+
+    begin
+      program.not_nil!.interpret
+    rescue ex : Util::ParserError
+      puts "Caught ParserError"
+      puts ex.message
+      exit(1)
+    end
   end
 end
 
diff --git a/src/util.cr b/src/util.cr
new file mode 100644
index 0000000..841a2b2
--- /dev/null
+++ b/src/util.cr
@@ -0,0 +1,5 @@
+module Util
+  class ParserError < Exception
+  end
+end
+