commit ece6e2f1880e52e98abcb7028e82b58c437724d8
Author: Russ Olsen <russ@russolsen.com>
Date:   Thu Aug 20 12:10:32 2015 -0400

    Initial checkin of Crystal port

diff --git a/.gitignore b/.gitignore
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+++ b/.gitignore
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+/.deps/
+/libs/
+/.crystal/
+/doc/
+crforth
+
+
diff --git a/.travis.yml b/.travis.yml
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+++ b/.travis.yml
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+language: c
+before_install: |
+  curl http://dist.crystal-lang.org/apt/setup.sh | sudo bash
+  sudo apt-get -q update
+
+install: |
+  sudo apt-get install crystal
+
+script:
+  - crystal spec
diff --git a/LICENSE b/LICENSE
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+++ b/LICENSE
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+The MIT License (MIT)
+
+Copyright (c) 2015 Russ Olsen
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/Makefile b/Makefile
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+++ b/Makefile
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+CR_FILES := $(wildcard src/*.cr) $(wildcard src/**/*.cr)
+
+crforth: $(CR_FILES)
+	crystal build -o $@ src/main.cr
+
+run:
+	crystal src/main.cr
+
+clean:
+	rm -f crforth
diff --git a/Projectfile b/Projectfile
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+++ b/Projectfile
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+deps do
+end
diff --git a/README.md b/README.md
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+++ b/README.md
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+# crforth
+
+A simple FORTH interpreter (http://github.com/russolsen/rforth) ported
+to the Crystal programming language.
+
+Note that CRForth is an experiment in porting a non-trivial application
+from Ruby to Crystal. The code is, as I write this, just barely working.
+This is probably not idiomatic Crystal -- I'm still figuring out what that
+means.
+
+Some lessons so far:
+
+* Most of the effort of the port involved minor changes to make the static typing
+happy. For example, FORTH interpreter uses a lot of procs whose return values are ignored.
+Eventually I had all of them return nil to make the static typing happy. I'm not sure
+if this is really the correct thing, but it was expediant.
+
+* The original Ruby version used metaprogramming to look at the methods available
+in a module. I've done that by hand in CRForth because I don't see the equivalent
+in Crystal.
+
+* It is really cool to get a stand alone, binary executable from Rubyish code.
+
+## Installation
+
+Add it to `Projectfile`
+
+```crystal
+deps do
+  github "[your-github-name]/crforth"
+end
+```
+
+## Usage
+
+```crystal
+require "crforth"
+
+i = CRForth::Interpreter.new
+i.run
+```
+
+Or just run the interpreter from source:
+
+```crystal
+crystal src/main.cr
+```
+
+Right now CRForth doesn't have a great interface: It just silently prompts for
+some FORTH code and executes it. To add 2 + 2 you would do the following:
+
+```
+~/projects/crystal/crforth: make run
+crystal src/main.cr
+2 2 + . cr
+4
+bye
+````
+
+## Development
+
+There is a Makefile for convience. The targets are:
+
+* crforth: Build the executable. This is the default.
+
+* clean: Clean up any generated files.
+
+* run: Runs the interpeter from source.
+
+## Contributing
+
+1. Fork it ( https://github.com/[your-github-name]/edn/fork )
+2. Create your feature branch (git checkout -b my-new-feature)
+3. Commit your changes (git commit -am 'Add some feature')
+4. Push to the branch (git push origin my-new-feature)
+5. Create a new Pull Request
+
+## Contributors
+
+- [russolsen](https://github.com/[russolsen]) Russ Olsen - creator, maintainer
diff --git a/spec/crforth_spec.cr b/spec/crforth_spec.cr
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index 0000000..e4ecaaa
--- /dev/null
+++ b/spec/crforth_spec.cr
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+require "./spec_helper"
+
+describe Crforth do
+  # TODO: Write tests
+
+  it "works" do
+    false.should eq(true)
+  end
+end
diff --git a/spec/spec_helper.cr b/spec/spec_helper.cr
new file mode 100644
index 0000000..58d6fe0
--- /dev/null
+++ b/spec/spec_helper.cr
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+require "spec"
+require "../src/crforth"
diff --git a/src/crforth.cr b/src/crforth.cr
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--- /dev/null
+++ b/src/crforth.cr
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+require "./crforth/*"
+
+module CRForth
+end
diff --git a/src/crforth/dictionary.cr b/src/crforth/dictionary.cr
new file mode 100644
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+++ b/src/crforth/dictionary.cr
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+module CRForth
+  class Entry
+    property! name, block, immediate
+  
+    def initialize(name: String, block: Proc(Nil), immediate: Bool)
+      @name = name
+      @block = block
+      @immediate = immediate
+    end
+  
+    def dup
+      Entry.new(@name, @block, @immediate)
+    end
+  end
+  
+  class Dictionary
+    def initialize
+      @entries = {} of String => Entry
+    end
+  
+    def word( name: String , &block: -> Nil )
+      @entries[name] = Entry.new(name, block, false)
+      nil
+    end
+  
+    def immediate_word( name: String , &block: -> Nil )
+      @entries[name] = Entry.new(name, block, true)
+    end
+  
+    def alias_word( name: String, old_name: String ): Bool
+      entry = @entries[name]
+      #raise "No such word #{old_name}" unless entry
+      if ! entry.is_a?(Nil)
+        new_entry = entry.dup
+        new_entry.name = name
+        @entries[name] = entry
+        true
+      else
+        false
+      end
+    end
+  
+    def get( name ): Entry?
+      # puts "Looking up #{name} in entries"
+      # puts @entries.keys
+      result = @entries[name]?
+      # puts "result: #{result.class}"
+      result
+    end
+  end
+end
diff --git a/src/crforth/interpreter.cr b/src/crforth/interpreter.cr
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+++ b/src/crforth/interpreter.cr
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+require "./dictionary"
+
+module CRForth
+  alias Num = (Int32 | Float64)
+  alias Anything = (Int32 | String | Float64 | Symbol | Nil)
+  
+  module PrimitiveWords
+    def dup
+      @stack << @stack.last
+      nil
+    end
+  
+    def q_dup
+      @stack << @stack.last unless @stack.last == 0
+      nil
+    end
+  
+    def drop
+      @stack.pop
+      nil
+    end
+  
+    def swap
+      @stack += [@stack.pop, @stack.pop]
+      nil
+    end
+  
+    def over
+      a = @stack.pop
+      b = @stack.pop
+      @stack << b << a << b
+      nil
+    end
+  
+    def rot
+      a = @stack.pop
+      b = @stack.pop
+      c = @stack.pop
+      @stack << b << a << c
+      nil
+    end
+  
+    def plus
+      a = @stack.pop as Num
+      b = @stack.pop as Num
+      @stack << a + b
+      nil
+    end
+  
+    def mult
+      a = @stack.pop as Num
+      b = @stack.pop as Num
+      @stack << a*b
+      nil
+    end
+  
+    def subtract
+      a = @stack.pop as Num
+      b = @stack.pop as Num
+      @stack << b - a
+      nil
+    end
+  
+    def divide
+      a = @stack.pop as Num
+      b = @stack.pop as Num
+      @stack << b / a
+      nil
+    end
+  
+    def dot
+      @s_out.print( @stack.pop )
+      nil
+    end
+  
+    def cr
+      @s_out.puts
+      nil
+    end
+  
+    def dot_s
+      @s_out.print( "#{@stack}\n" )
+      nil
+    end
+  
+    def dot_d
+      pp @dictionary
+      nil
+    end
+  
+    def hello
+      puts "hello"
+      nil
+    end
+  end
+  
+  class Interpreter
+    include PrimitiveWords
+  
+    def initialize( s_in = STDIN, s_out = STDOUT )
+      @s_in = s_in
+      @s_out = s_out
+      @dictionary = Dictionary.new
+      @stack = [] of Anything
+      initialize_dictionary
+    end
+  
+    # Create all of the initial words.
+    def initialize_dictionary
+      word(":") do
+        read_and_define_word
+      end
+  
+      immediate_word( "\\" ) { @s_in.read_line; nil }
+      word("bye"){ exit }
+      word("+") {plus}
+      word(".") {dot}
+      word(".d") {dot_d}
+      word(".s") {dot_s}
+      word("*") {mult}
+      word("-") {subtract}
+      word("/") {divide}
+      word("cr") {cr}
+      word("hello") {hello}
+    end
+  
+    # Convience method that takes a word and a closure
+    # and defines the word in the dictionary
+    def word( name, &block: -> Nil )
+      @dictionary.word( name, &block )
+    end
+  
+    # Convience method that takes a word and a closure
+    # and defines an immediate word in the dictionary
+    def immediate_word( name, &block: -> Nil )
+      @dictionary.immediate_word( name, &block )
+    end
+  
+    # Convience method that takes an existing dict.
+    # word and a new word and aliases the new word to
+    # the old.
+    def alias_word( name: String, old_name: String )
+      @dictionary.alias_word( name, old_name )
+    end
+  
+    # Given the name of a new words and the words
+    # that make up its definition, define the
+    # new word.
+    def define_word( name: String , words: Array(String) )
+      @dictionary.word( name, &compile_words( words ) )
+    end
+  
+    # Give an array of (string) words, return
+    # A block which will run all of those words.
+    # Executes all immedate words, well, immediately.
+    def compile_words( words: Array(String) )
+      blocks = [] of Proc(Nil)
+      words.each do |word|
+        entry = resolve_word( word )
+        raise "no such word: #{word}" unless entry
+        if entry.immediate
+          entry.block.call
+        else
+          blocks << entry.block
+        end
+      end
+      Proc(Nil).new{blocks.each {|b| b.call}; nil}
+    end
+  
+    # Read a word definition from input and
+    # define the word
+    # Definition looks like:
+    #  new-word w1 w2 w3 ;
+    def read_and_define_word
+      name = read_word
+      words = [] of String
+      while (word = read_word)
+        break if word == ";"
+        words << word
+      end
+      unless name.is_a?(Nil)
+        @dictionary.word(name, &compile_words(words))
+      end
+    end
+  
+    # Given a (string) word, return the dictionary
+    # entry for that word or nil.
+    def resolve_word( word: String ): Entry | Nil
+      return @dictionary.get(word) unless  @dictionary.get(word).is_a?(Nil)
+      x = to_number(word)
+      unless x.is_a?(Nil)
+        block = ->{push_number(x)}
+        return Entry.new(word, block, false)
+      end
+      nil
+    end
+  
+    def push_number(x: Nil | Int32 | Float64)
+      @stack << x
+      nil
+    end
+  
+    # Evaluate the given word.
+    def forth_eval( word: String )
+      entry = resolve_word(word)
+      if entry.is_a?(Nil)
+        @s_out.puts "#{word} ??"
+      elsif entry.block.is_a?(Nil)
+        @s_out.puts "#{word} ??"
+      else
+        entry.block.call
+      end
+    end
+  
+    def forth_eval(word: Nil)
+      puts "Cant evaluate nil"
+    end
+  
+    def to_float(word : String) : Float64?
+      begin
+       word.to_f
+      rescue
+       nil
+      end
+    end
+  
+    def to_int(word : String) : Int32?
+      begin
+       word.to_i
+      rescue
+       nil
+      end
+    end
+  
+    # Try to turn the word into a number, return nil if
+    # conversion fails
+    def to_number( word )
+      if word.is_a?(Nil)
+        return nil
+      elsif (x = to_int(word))
+        return x
+      elsif (x = to_float(word))
+        return x
+      end
+    end
+  
+    def read_word: String?
+      result = nil
+      ch = nil
+      while true
+        start_line = false
+
+        ch = @s_in.read_char
+        if ch.is_a?(Nil)
+          break
+        elsif result && ch.whitespace?
+          break
+        elsif result.is_a?(Nil)
+          result = ch.to_s
+        else
+          result += ch
+        end
+      end
+      return result if result
+      nil
+    end
+  
+    def read_string: String
+    end
+  
+    def run
+      while true
+        word = read_word
+        break unless word
+        forth_eval( word )
+        @s_out.flush
+      end
+    end
+  end
+end
diff --git a/src/crforth/version.cr b/src/crforth/version.cr
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+++ b/src/crforth/version.cr
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+module CRForth
+  VERSION = "0.0.1"
+end
diff --git a/src/main.cr b/src/main.cr
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+++ b/src/main.cr
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+require "./crforth"
+
+CRForth::Interpreter.new.run