scryer-prolog 0.8.68

A modern Prolog implementation written mostly in Rust.
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use prolog_parser::ast::*;

use prolog::clause_types::*;
use prolog::forms::*;

use std::collections::{HashMap, VecDeque};

pub enum ChoiceInstruction {
    DefaultRetryMeElse(usize),
    DefaultTrustMe,
    RetryMeElse(usize),
    TrustMe,
    TryMeElse(usize)
}

pub enum CutInstruction {
    Cut(RegType),
    GetLevel(RegType),
    GetLevelAndUnify(RegType),
    NeckCut
}

pub enum IndexedChoiceInstruction {
    Retry(usize),
    Trust(usize),
    Try(usize)
}

impl From<IndexedChoiceInstruction> for Line {
    fn from(i: IndexedChoiceInstruction) -> Self {
        Line::IndexedChoice(i)
    }
}

impl IndexedChoiceInstruction {
    pub fn offset(&self) -> usize {
        match self {
            &IndexedChoiceInstruction::Retry(offset) => offset,
            &IndexedChoiceInstruction::Trust(offset) => offset,
            &IndexedChoiceInstruction::Try(offset)   => offset
        }
    }
}

pub enum Line {
    Arithmetic(ArithmeticInstruction),
    Choice(ChoiceInstruction),
    Control(ControlInstruction),
    Cut(CutInstruction),
    Fact(FactInstruction),
    Indexing(IndexingInstruction),
    IndexedChoice(IndexedChoiceInstruction),
    Query(QueryInstruction)
}

impl Line {
    pub fn is_head_instr(&self) -> bool {
        match self {
            &Line::Cut(_) => true,            
            &Line::Fact(_) => true,
            &Line::Query(_) => true,
            _ => false
        }
    }
}

#[derive(Clone)]
pub enum ArithmeticInstruction {
    Add(ArithmeticTerm, ArithmeticTerm, usize),
    Sub(ArithmeticTerm, ArithmeticTerm, usize),
    Mul(ArithmeticTerm, ArithmeticTerm, usize),
    Pow(ArithmeticTerm, ArithmeticTerm, usize),
    IntPow(ArithmeticTerm, ArithmeticTerm, usize),
    IDiv(ArithmeticTerm, ArithmeticTerm, usize),
    Max(ArithmeticTerm, ArithmeticTerm, usize),
    FIDiv(ArithmeticTerm, ArithmeticTerm, usize),
    RDiv(ArithmeticTerm, ArithmeticTerm, usize),
    Div(ArithmeticTerm, ArithmeticTerm, usize),
    Shl(ArithmeticTerm, ArithmeticTerm, usize),
    Shr(ArithmeticTerm, ArithmeticTerm, usize),
    Xor(ArithmeticTerm, ArithmeticTerm, usize),
    And(ArithmeticTerm, ArithmeticTerm, usize),
    Or(ArithmeticTerm, ArithmeticTerm, usize),
    Mod(ArithmeticTerm, ArithmeticTerm, usize),
    Rem(ArithmeticTerm, ArithmeticTerm, usize),
    Abs(ArithmeticTerm, usize),
    Neg(ArithmeticTerm, usize),
}

pub enum ControlInstruction {
    Allocate(usize), // num_frames.
    // name, arity, perm_vars after threshold, last call, use default call policy.
    CallClause(ClauseType, usize, usize, bool, bool),
    Deallocate,
    JmpBy(usize, usize, usize, bool), // arity, global_offset, perm_vars after threshold, last call.
    Proceed
}

impl ControlInstruction {
    pub fn is_jump_instr(&self) -> bool {
        match self {
            &ControlInstruction::CallClause(..)  => true,
            &ControlInstruction::JmpBy(..) => true,
            _ => false
        }
    }
}

pub enum IndexingInstruction {
    SwitchOnTerm(usize, usize, usize, usize),
    SwitchOnConstant(usize, HashMap<Constant, usize>),
    SwitchOnStructure(usize, HashMap<(ClauseName, usize), usize>)
}

impl From<IndexingInstruction> for Line {
    fn from(i: IndexingInstruction) -> Self {
        Line::Indexing(i)
    }
}

#[derive(Clone)]
pub enum FactInstruction {
    GetConstant(Level, Constant, RegType),
    GetList(Level, RegType),
    GetStructure(ClauseType, usize, RegType),
    GetValue(RegType, usize),
    GetVariable(RegType, usize),
    UnifyConstant(Constant),
    UnifyLocalValue(RegType),
    UnifyVariable(RegType),
    UnifyValue(RegType),
    UnifyVoid(usize)
}

#[derive(Clone)]
pub enum QueryInstruction {
    GetVariable(RegType, usize),
    PutConstant(Level, Constant, RegType),
    PutList(Level, RegType),
    PutStructure(ClauseType, usize, RegType),
    PutUnsafeValue(usize, usize),
    PutValue(RegType, usize),
    PutVariable(RegType, usize),
    SetConstant(Constant),
    SetLocalValue(RegType),
    SetVariable(RegType),
    SetValue(RegType),
    SetVoid(usize)
}

pub type CompiledFact = Vec<FactInstruction>;

pub type ThirdLevelIndex = Vec<IndexedChoiceInstruction>;

pub type Code = Vec<Line>;

pub type CodeDeque = VecDeque<Line>;