prolog

package module
v0.1.0 Latest Latest
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 Go to latest Published: Feb 27, 2021 License: MIT Imports: 13 Imported by: 32

README

ichiban/prolog

A minimal prolog interpreter based on ZIP.

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var DefaultFunctionSet = FunctionSet{
	Unary: map[Atom]func(Term) (Term, error){
		"-":        unaryNumber(func(i int64) int64 { return -1 * i }, func(n float64) float64 { return -1 * n }),
		"abs":      unaryFloat(math.Abs),
		"atan":     unaryFloat(math.Atan),
		"ceiling":  unaryFloat(math.Ceil),
		"cos":      unaryFloat(math.Cos),
		"exp":      unaryFloat(math.Exp),
		"sqrt":     unaryFloat(math.Sqrt),
		"sign":     unaryNumber(sgn, sgnf),
		"float":    unaryFloat(func(n float64) float64 { return n }),
		"floor":    unaryFloat(math.Floor),
		"log":      unaryFloat(math.Log),
		"sin":      unaryFloat(math.Sin),
		"truncate": unaryFloat(math.Trunc),
		"round":    unaryFloat(math.Round),
		"\\":       unaryInteger(func(i int64) int64 { return ^i }),
	},
	Binary: map[Atom]func(Term, Term) (Term, error){
		"+":   binaryNumber(func(i, j int64) int64 { return i + j }, func(n, m float64) float64 { return n + m }),
		"-":   binaryNumber(func(i, j int64) int64 { return i - j }, func(n, m float64) float64 { return n - m }),
		"*":   binaryNumber(func(i, j int64) int64 { return i * j }, func(n, m float64) float64 { return n * m }),
		"/":   binaryFloat(func(n float64, m float64) float64 { return n / m }),
		"//":  binaryInteger(func(i, j int64) int64 { return i / j }),
		"rem": binaryInteger(func(i, j int64) int64 { return i % j }),
		"mod": binaryInteger(func(i, j int64) int64 { return (i%j + j) % j }),
		"**":  binaryFloat(math.Pow),
		">>":  binaryInteger(func(i, j int64) int64 { return i >> j }),
		"<<":  binaryInteger(func(i, j int64) int64 { return i << j }),
		"/\\": binaryInteger(func(i, j int64) int64 { return i & j }),
		"\\/": binaryInteger(func(i, j int64) int64 { return i | j }),
	},
}

Functions

func Arg 

func Arg(arg, term, value Term, k func() (bool, error)) (bool, error)

func AtomChars 

func AtomChars(atom, chars Term, k func() (bool, error)) (bool, error)

func AtomCodes 

func AtomCodes(atom, codes Term, k func() (bool, error)) (bool, error)

func AtomConcat 

func AtomConcat(atom1, atom2, atom3 Term, k func() (bool, error)) (bool, error)

func AtomLength 

func AtomLength(atom, integer Term, k func() (bool, error)) (bool, error)

func CharCode 

func CharCode(char, code Term, k func() (bool, error)) (bool, error)

func Compare 

func Compare(order, term1, term2 Term, k func() (bool, error)) (bool, error)

func Contains 

func Contains(t, s Term) bool

Contains checks if t contains s.

func CopyTerm 

func CopyTerm(in, out Term, k func() (bool, error)) (bool, error)

func Cut 

func Cut(k func() (bool, error)) (bool, error)

func Done 

func Done() (bool, error)

Done terminates a continuation chain.

func Each 

func Each(list Term, f func(elem Term) error) error

Each iterates over list.

func Functor 

func Functor(term, name, arity Term, k func() (bool, error)) (bool, error)

func NumberChars 

func NumberChars(num, chars Term, k func() (bool, error)) (bool, error)

func NumberCodes 

func NumberCodes(num, chars Term, k func() (bool, error)) (bool, error)

func Repeat 

func Repeat(k func() (bool, error)) (bool, error)

func SubAtom 

func SubAtom(atom, before, length, after, subAtom Term, k func() (bool, error)) (bool, error)

func Throw 

func Throw(t Term, _ func() (bool, error)) (bool, error)

func TypeAtom 

func TypeAtom(t Term, k func() (bool, error)) (bool, error)

func TypeCompound 

func TypeCompound(t Term, k func() (bool, error)) (bool, error)

func TypeFloat 

func TypeFloat(t Term, k func() (bool, error)) (bool, error)

func TypeInteger 

func TypeInteger(t Term, k func() (bool, error)) (bool, error)

func TypeVar 

func TypeVar(t Term, k func() (bool, error)) (bool, error)

func Unify 

func Unify(t1, t2 Term, k func() (bool, error)) (bool, error)

func UnifyWithOccursCheck 

func UnifyWithOccursCheck(t1, t2 Term, k func() (bool, error)) (bool, error)

func Univ 

func Univ(term, list Term, k func() (bool, error)) (bool, error)

Types

type Atom 

type Atom string

Atom is a prolog atom.

func (Atom) Copy 

func (a Atom) Copy() Term

Copy simply returns the atom.

func (Atom) String 

func (a Atom) String() string

func (Atom) Unify 

func (a Atom) Unify(t Term, occursCheck bool) bool

Unify unifies the atom with t.

func (Atom) WriteTerm 

func (a Atom) WriteTerm(w io.Writer, opts WriteTermOptions) error

WriteTerm writes the atom into w.

type Compound 

type Compound struct {
	Functor Atom
	Args    []Term
}

Compound is a prolog compound.

func (*Compound) Copy 

func (c *Compound) Copy() Term

Copy returns a fresh compound with copies of arguments.

func (*Compound) String 

func (c *Compound) String() string

func (*Compound) Unify 

func (c *Compound) Unify(t Term, occursCheck bool) bool

Unify unifies the compound with t.

func (*Compound) WriteTerm 

func (c *Compound) WriteTerm(w io.Writer, opts WriteTermOptions) error

WriteTerm writes the compound into w.

type Engine 

type Engine struct {
	EngineState
}

Engine is a Prolog interpreter. The zero value for Engine is a valid interpreter without any builtin predicates.

func NewEngine 

func NewEngine(in io.Reader, out io.Writer) (*Engine, error)

NewEngine creates an Engine with user_input, user_output and builtin predicates. It is encouraged user_input to be *bufio.Reader since it enables a wide range of input operations.

func (*Engine) Describe 

func (e *Engine) Describe(v *Variable) string

Describe stringifies the given variable in the format of 'V = f(a, b)'.

func (*Engine) Exec 

func (e *Engine) Exec(s string) error

Exec executes a prolog program.

func (*Engine) Query 

func (e *Engine) Query(s string, cb func(vars []*Variable) bool) (bool, error)

Query executes a prolog query and calls the callback function for each solution. Returning true from the callback halts the iteration.

func (*Engine) Register0 

func (e *Engine) Register0(name string, p func(func() (bool, error)) (bool, error))

Register0 registers a predicate of arity 0.

func (*Engine) Register1 

func (e *Engine) Register1(name string, p func(Term, func() (bool, error)) (bool, error))

Register1 registers a predicate of arity 1.

func (*Engine) Register2 

func (e *Engine) Register2(name string, p func(Term, Term, func() (bool, error)) (bool, error))

Register2 registers a predicate of arity 2.

func (*Engine) Register3 

func (e *Engine) Register3(name string, p func(Term, Term, Term, func() (bool, error)) (bool, error))

Register3 registers a predicate of arity 3.

func (*Engine) Register4 

func (e *Engine) Register4(name string, p func(Term, Term, Term, Term, func() (bool, error)) (bool, error))

Register4 registers a predicate of arity 4.

func (*Engine) Register5 

func (e *Engine) Register5(name string, p func(Term, Term, Term, Term, Term, func() (bool, error)) (bool, error))

Register5 registers a predicate of arity 5.

type EngineState 

type EngineState struct {
	// BeforeHalt is a hook which gets triggered right before halt/0 or halt/1.
	BeforeHalt []func()
	// contains filtered or unexported fields
}

EngineState is an internal state of Engine, a subject to many builtin predicates.

func (*EngineState) Abolish 

func (e *EngineState) Abolish(t Term, k func() (bool, error)) (bool, error)

func (*EngineState) Asserta 

func (e *EngineState) Asserta(t Term, k func() (bool, error)) (bool, error)

func (*EngineState) Assertz 

func (e *EngineState) Assertz(t Term, k func() (bool, error)) (bool, error)

func (*EngineState) BagOf 

func (e *EngineState) BagOf(template, goal, bag Term, k func() (bool, error)) (bool, error)

func (*EngineState) Call 

func (e *EngineState) Call(goal Term, k func() (bool, error)) (bool, error)

func (*EngineState) Catch 

func (e *EngineState) Catch(goal, catcher, recover Term, k func() (bool, error)) (bool, error)

func (*EngineState) CharConversion 

func (e *EngineState) CharConversion(char1, char2 Term, k func() (bool, error)) (bool, error)

func (*EngineState) Clause 

func (e *EngineState) Clause(head, body Term, k func() (bool, error)) (bool, error)

func (*EngineState) Close 

func (e *EngineState) Close(stream, options Term, k func() (bool, error)) (bool, error)

func (*EngineState) CurrentCharConversion 

func (e *EngineState) CurrentCharConversion(char1, char2 Term, k func() (bool, error)) (bool, error)

func (*EngineState) CurrentInput 

func (e *EngineState) CurrentInput(stream Term, k func() (bool, error)) (bool, error)

func (*EngineState) CurrentOp 

func (e *EngineState) CurrentOp(precedence, typ, name Term, k func() (bool, error)) (bool, error)

func (*EngineState) CurrentOutput 

func (e *EngineState) CurrentOutput(stream Term, k func() (bool, error)) (bool, error)

func (*EngineState) CurrentPredicate 

func (e *EngineState) CurrentPredicate(pf Term, k func() (bool, error)) (bool, error)

func (*EngineState) CurrentPrologFlag 

func (e *EngineState) CurrentPrologFlag(flag, value Term, k func() (bool, error)) (bool, error)

func (*EngineState) FlushOutput 

func (e *EngineState) FlushOutput(stream Term, k func() (bool, error)) (bool, error)

func (*EngineState) GetByte 

func (e *EngineState) GetByte(stream, byt Term, k func() (bool, error)) (bool, error)

func (*EngineState) GetCode 

func (e *EngineState) GetCode(stream, code Term, k func() (bool, error)) (bool, error)

func (*EngineState) Halt 

func (e *EngineState) Halt(n Term, k func() (bool, error)) (bool, error)

func (*EngineState) Op 

func (e *EngineState) Op(precedence, typ, name Term, k func() (bool, error)) (bool, error)

func (*EngineState) Open 

func (e *EngineState) Open(filename, mode, stream, options Term, k func() (bool, error)) (bool, error)

func (*EngineState) PeekByte 

func (e *EngineState) PeekByte(stream, byt Term, k func() (bool, error)) (bool, error)

func (*EngineState) PeekCode 

func (e *EngineState) PeekCode(stream, code Term, k func() (bool, error)) (bool, error)

func (*EngineState) PutByte 

func (e *EngineState) PutByte(stream, byt Term, k func() (bool, error)) (bool, error)

func (*EngineState) PutCode 

func (e *EngineState) PutCode(stream, code Term, k func() (bool, error)) (bool, error)

func (*EngineState) ReadTerm 

func (e *EngineState) ReadTerm(stream, term, options Term, k func() (bool, error)) (bool, error)

func (*EngineState) Retract 

func (e *EngineState) Retract(t Term, k func() (bool, error)) (bool, error)

func (*EngineState) SetInput 

func (e *EngineState) SetInput(stream Term, k func() (bool, error)) (bool, error)

func (*EngineState) SetOf 

func (e *EngineState) SetOf(template, goal, bag Term, k func() (bool, error)) (bool, error)

func (*EngineState) SetOutput 

func (e *EngineState) SetOutput(stream Term, k func() (bool, error)) (bool, error)

func (*EngineState) SetPrologFlag 

func (e *EngineState) SetPrologFlag(flag, value Term, k func() (bool, error)) (bool, error)

func (*EngineState) SetStreamPosition 

func (e *EngineState) SetStreamPosition(stream, pos Term, k func() (bool, error)) (bool, error)

func (*EngineState) StreamProperty 

func (e *EngineState) StreamProperty(stream, property Term, k func() (bool, error)) (bool, error)

func (*EngineState) WriteTerm 

func (e *EngineState) WriteTerm(stream, term, options Term, k func() (bool, error)) (bool, error)

type Exception 

type Exception struct {
	Term
}

func (*Exception) Error 

func (e *Exception) Error() string

type Float 

type Float float64

Float is a prolog floating-point number.

func (Float) Copy 

func (f Float) Copy() Term

Copy simply returns the float.

func (Float) String 

func (f Float) String() string

func (Float) Unify 

func (f Float) Unify(t Term, occursCheck bool) bool

Unify unifies the float with t.

func (Float) WriteTerm 

func (f Float) WriteTerm(w io.Writer, _ WriteTermOptions) error

WriteTerm writes the float into w.

type FunctionSet 

type FunctionSet struct {
	Unary  map[Atom]func(x Term) (Term, error)
	Binary map[Atom]func(x, y Term) (Term, error)
}

func (FunctionSet) Equal 

func (fs FunctionSet) Equal(lhs, rhs Term, k func() (bool, error)) (bool, error)

func (FunctionSet) GreaterThan 

func (fs FunctionSet) GreaterThan(lhs, rhs Term, k func() (bool, error)) (bool, error)

func (FunctionSet) GreaterThanOrEqual 

func (fs FunctionSet) GreaterThanOrEqual(lhs, rhs Term, k func() (bool, error)) (bool, error)

func (FunctionSet) Is 

func (fs FunctionSet) Is(lhs, rhs Term, k func() (bool, error)) (bool, error)

func (FunctionSet) LessThan 

func (fs FunctionSet) LessThan(lhs, rhs Term, k func() (bool, error)) (bool, error)

func (FunctionSet) LessThanOrEqual 

func (fs FunctionSet) LessThanOrEqual(lhs, rhs Term, k func() (bool, error)) (bool, error)

func (FunctionSet) NotEqual 

func (fs FunctionSet) NotEqual(lhs, rhs Term, k func() (bool, error)) (bool, error)

type Integer 

type Integer int64

Integer is a prolog integer.

func (Integer) Copy 

func (i Integer) Copy() Term

Copy simply returns the integer.

func (Integer) String 

func (i Integer) String() string

func (Integer) Unify 

func (i Integer) Unify(t Term, occursCheck bool) bool

Unify unifies the integer with t.

func (Integer) WriteTerm 

func (i Integer) WriteTerm(w io.Writer, _ WriteTermOptions) error

WriteTerm writes the integer into w.

type Operator 

type Operator struct {
	Precedence Integer // 1 ~ 1200
	Type       Atom
	Name       Atom
}

Operator is an operator definition.

type Operators 

type Operators []Operator

Operators are a list of operators sorted in a descending order of precedence.

type Parser 

type Parser struct {
	// contains filtered or unexported fields
}

Parser turns bytes into Term.

func NewParser 

func NewParser(input *bufio.Reader, operators *Operators, charConversions map[rune]rune) *Parser

NewParser creates a Parser.

func (*Parser) Clause 

func (p *Parser) Clause() (Term, error)

Clause parses a clause, term followed by a full stop.

func (*Parser) Term 

func (p *Parser) Term() (Term, error)

Term parses a term.

type Stream 

type Stream struct {
	io.Reader
	io.Writer
	io.Closer
	// contains filtered or unexported fields
}

Stream is a prolog stream.

func (*Stream) Copy 

func (s *Stream) Copy() Term

Copy simply returns the stream.

func (*Stream) String 

func (s *Stream) String() string

func (*Stream) Unify 

func (s *Stream) Unify(t Term, occursCheck bool) bool

Unify unifies the stream with t.

func (*Stream) WriteTerm 

func (s *Stream) WriteTerm(w io.Writer, _ WriteTermOptions) error

WriteTerm writes the stream into w.

type Term 

type Term interface {
	fmt.Stringer
	WriteTerm(io.Writer, WriteTermOptions) error
	Unify(Term, bool) bool
	Copy() Term
}

Term is a prolog term.

func Cons 

func Cons(car, cdr Term) Term

Cons returns a list consists of a first element car and the rest cdr.

func List 

func List(ts ...Term) Term

List returns a list of ts.

func ListRest 

func ListRest(rest Term, ts ...Term) Term

ListRest returns a list of ts prepended by rest.

func PrincipalFunctor 

func PrincipalFunctor(name Atom, arity Integer) Term

PrincipalFunctor returns a compound of name/arity.

func Resolve 

func Resolve(t Term) Term

Resolve follows the variable chain and returns the first non-variable term or the last free variable.

func Rulify 

func Rulify(t Term) Term

Rulify returns t if t is in a form of P:-Q, t:-true otherwise.

func Set 

func Set(ts ...Term) Term

Set returns a list of ts which elements are unique.

type Variable 

type Variable struct {
	Name string
	Ref  Term
}

Variable is a prolog variable.

func (*Variable) Copy 

func (v *Variable) Copy() Term

Copy returns a fresh variable with a copy of Ref.

func (*Variable) String 

func (v *Variable) String() string

func (*Variable) Unify 

func (v *Variable) Unify(t Term, occursCheck bool) bool

Unify unifies the variable with t.

func (*Variable) WriteTerm 

func (v *Variable) WriteTerm(w io.Writer, opts WriteTermOptions) error

WriteTerm writes the variable into w.

type WriteTermOptions 

type WriteTermOptions struct {
	Quoted      bool
	Ops         Operators
	NumberVars  bool
	Descriptive bool
}

WriteTermOptions describes options to write terms.

Source Files

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