require "fileutils"

describe Propane do
  def write_grammar(grammar)
    File.write("spec/run/testparser.propane", grammar)
  end

  def build_parser
    result = system(*%w[./propane.sh spec/run/testparser.propane spec/run/testparser.d])
    expect(result).to be_truthy
  end

  def compile(test_file)
    result = system(*%w[gdc -funittest -o spec/run/testparser spec/run/testparser.d], test_file)
    expect(result).to be_truthy
  end

  def run
    result = system("spec/run/testparser")
    expect(result).to be_truthy
  end

  before(:each) do
    FileUtils.rm_rf("spec/run")
    FileUtils.mkdir_p("spec/run")
  end

  it "generates a D lexer" do
    write_grammar <<EOF
token int \\d+
token plus \\+
token times \\*
drop \\s+
Start: [Foo] <<
>>
Foo: [int] <<
>>
Foo: [plus] <<
>>
EOF
    build_parser
    compile("spec/test_d_lexer.d")
    run
  end

  it "generates a parser" do
    write_grammar <<EOF
token plus \\+
token times \\*
token zero 0
token one 1
Start: [E] <<
>>
E: [E times B] <<
>>
E: [E plus B] <<
>>
E: [B] <<
>>
B: [zero] <<
>>
B: [one] <<
>>
EOF
    build_parser
  end

  it "distinguishes between multiple identical rules with lookahead symbol" do
    write_grammar <<EOF
token a
token b
Start: [R1 a] <<
>>
Start: [R2 b] <<
>>
R1: [a b] <<
>>
R2: [a b] <<
>>
EOF
    build_parser
  end

  it "handles reducing a rule that could be arrived at from multiple states" do
    write_grammar <<EOF
token a
token b
Start: [a R1] <<
>>
Start: [b R1] <<
>>
R1: [b] <<
>>
EOF
    build_parser
  end
end