wolfpack-parser 0.1.0

The parser of wolfpack. Internal part of wolfpack-lang, not a stable API
Documentation 
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---
source: crates/wolf_parser/tests/parser.rs
expression: result.dump
---
file
  doc! " A reverse Polish notation calculator: enums with data, `Result`, the `?` operator, a user"
  doc! " error type that implements `Error`, and `main` returning a `Result`."
  module main
  section types
    enum
      CalcError
      (variant BadToken (tuple String))
      (variant StackUnderflow)
      (variant DivisionByZero)
      (variant Unbalanced (tuple Int))
  section impl
    impl
      CalcError
      (for Error)
      fn
        message
        (params self)
        (-> String)
        block
          match
            self
            (=> (CalcError.BadToken token) (+ "bad token: " token))
            (=> CalcError.StackUnderflow "not enough operands")
            (=> CalcError.DivisionByZero "division by zero")
            =>
              (CalcError.Unbalanced count)
              (+ (call (. count to_string)) " values left on the stack")
  section functions
    fn
      pop
      (params (mut stack (List Int)))
      (-> (Result Int CalcError))
      block
        match
          (call (. stack pop))
          (=> (Some value) (call Ok value))
          (=> None (call Err (. CalcError StackUnderflow)))
    fn
      apply
      (params (op String) (a Int) (b Int))
      (-> (Result Int CalcError))
      block
        match
          op
          (=> "+" (call Ok (+ a b)))
          (=> "-" (call Ok (- a b)))
          (=> "*" (call Ok (* a b)))
          =>
            "/"
            if
              (== b 0)
              (block (call Err (. CalcError DivisionByZero)))
              (else (block (call Ok (/ a b))))
          (=> _ (call Err (call (. CalcError BadToken) (call (. op copy)))))
    fn
      is_operator
      (params (token String))
      (-> Bool)
      (block (|| (|| (|| (== token "+") (== token "-")) (== token "*")) (== token "/")))
    fn
      doc " Evaluates tokens separated by single spaces, for example `3 4 + 2 *`."
      evaluate
      (params (text String))
      (-> (Result Int CalcError))
      block
        (var stack (List Int) [])
        for
          token
          (call (. text split) " ")
          block
            if
              (call is_operator token)
              block
                (let b (? (call pop (mut stack))))
                (let a (? (call pop (mut stack))))
                (call (. stack push) (? (call apply token a b)))
              else
                block
                  match
                    (call (. token parse_int))
                    (=> (Ok number) (call (. stack push) number))
                    =>
                      (Err _)
                      (return (call Err (call (. CalcError BadToken) (call (. token copy)))))
        (let result (? (call pop (mut stack))))
        if
          (! (call (. stack is_empty)))
          (block (return (call Err (call (. CalcError Unbalanced) (+ (call (. stack len)) 1)))))
        (call Ok result)
    fn
      main
      ()
      (-> (Result Void Error))
      block
        for
          line
          (list "3 4 +" "5 1 2 + 4 * + 3 -" "2 3 4 * +" "10 2 /")
          (block (call print (+ (+ line " = ") (call (. (? (call evaluate line)) to_string)))))
        for
          line
          (list "1 +" "4 0 /" "1 2" "2 x *")
          block
            match
              (call evaluate line)
              (=> (Ok value) (call print (+ (+ line " = ") (call (. value to_string)))))
              (=> (Err error) (call print (+ (+ line ": ") (call (. error message)))))
        (call Ok ())
  section tests
    (test "adds two numbers" (block (call assert (== (call evaluate "2 3 +") (call Ok 5)))))
    (test "respects operand order" (block (call assert (== (call evaluate "10 4 -") (call Ok 6)))))
    test
      "reports division by zero"
      (block (call assert (== (call evaluate "1 0 /") (call Err (. CalcError DivisionByZero)))))
    test
      "reports a bad token"
      block
        (call assert (== (call evaluate "1 a +") (call Err (call (. CalcError BadToken) "a"))))