「RubyでつくるRuby」の interp.rb

#MinRuby

Rubyで学ぶRuby 第9回インタプリタの完成、そしてブートストラップへ

https://ascii.jp/elem/000/001/419/1419659/

code:interp.rb

require "minruby"

def evaluate(tree, genv, lenv)

case tree0

when "lit"

tree1

when "+"

evaluate(tree1, genv, lenv) + evaluate(tree2, genv, lenv)

when "-"

evaluate(tree1, genv, lenv) - evaluate(tree2, genv, lenv)

when "*"

evaluate(tree1, genv, lenv) * evaluate(tree2, genv, lenv)

when "/"

evaluate(tree1, genv, lenv) / evaluate(tree2, genv, lenv)

when "%"

evaluate(tree1, genv, lenv) % evaluate(tree2, genv, lenv)

when "<"

evaluate(tree1, genv, lenv) < evaluate(tree2, genv, lenv)

when "<="

evaluate(tree1, genv, lenv) <= evaluate(tree2, genv, lenv)

when "=="

evaluate(tree1, genv, lenv) == evaluate(tree2, genv, lenv)

when "!="

evaluate(tree1, genv, lenv) != evaluate(tree2, genv, lenv)

when ">="

evaluate(tree1, genv, lenv) >= evaluate(tree2, genv, lenv)

when ">"

evaluate(tree1, genv, lenv) > evaluate(tree2, genv, lenv)

when "stmts"

i = 1

last = nil

while treei

last = evaluate(treei, genv, lenv)

i = i + 1

end

last

when "var_assign"

lenv[tree1] = evaluate(tree2, genv, lenv)

when "var_ref"

lenv[tree1]

when "if"

if evaluate(tree1, genv, lenv)

evaluate(tree2, genv, lenv)

else

evaluate(tree3, genv, lenv)

end

when "while"

while evaluate(tree1, genv, lenv)

evaluate(tree2, genv, lenv)

end

when "func_def"

genv[tree1] = ["user_defined", tree2, tree3]

when "func_call"

args = []

i = 0

while treei + 2

argsi = evaluate(treei + 2, genv, lenv)

i = i + 1

end

mhd = genv[tree1]

if mhd0 == "builtin"

minruby_call(mhd1, args)

else

new_lenv = {}

params = mhd1

i = 0

while paramsi

new_lenv[paramsi] = argsi

i = i + 1

end

evaluate(mhd2, genv, new_lenv)

end

when "ary_new"

ary = []

i = 0

while treei + 1

aryi = evaluate(treei + 1, genv, lenv)

i = i + 1

end

ary

when "ary_ref"

ary = evaluate(tree1, genv, lenv)

idx = evaluate(tree2, genv, lenv)

aryidx

when "ary_assign"

ary = evaluate(tree1, genv, lenv)

idx = evaluate(tree2, genv, lenv)

val = evaluate(tree3, genv, lenv)

aryidx = val

when "hash_new"

hsh = {}

i = 0

while treei + 1

key = evaluate(treei + 1, genv, lenv)

val = evaluate(treei + 2, genv, lenv)

hshkey = val

i = i + 2

end

hsh

end

# ① プログラムの文字列を読み込む

str = minruby_load()

# ② プログラムの文字列を抽象構文木に変換する

tree = minruby_parse(str)

# ③ 抽象構文木を実行（計算）する

genv = {

"p" => "builtin", "p",

"require" => "builtin", "require",

"minruby_parse" => "builtin", "minruby_parse",

"minruby_load" => "builtin", "minruby_load",

"minruby_call" => "builtin", "minruby_call",

}

lenv = {}

evaluate(tree, genv, lenv)