eval

package
v0.2.0 Latest Latest
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 Go to latest Published: May 31, 2023 License: EUPL-1.2 Imports: 6 Imported by: 1

Documentation

Overview

Package eval allows to evaluate s-expressions. Evaluation is splitted into parsing that s-expression and executing the result of the parsed expression. This is done to reduce syntax checks.

Index

Constants

This section is empty.

Variables

View Source 
var FalseExpr = falseExpr{}

FalseExpr returns always False

View Source 
var NilExpr = nilExpr{}

NilExpr returns always Nil

View Source 
var TrueExpr = trueExpr{}

TrueExpr returns always True

Functions

This section is empty.

Types

type Builtin 

type Builtin interface {
	sxpf.Object
	Callable

	Name(*Engine) string
}

Builtin is a callable with a name

type BuiltinA 

type BuiltinA func([]sxpf.Object) (sxpf.Object, error)

BuiltinA is the signature of all normal builtin functions.

func (BuiltinA) Call 

func (b BuiltinA) Call(eng *Engine, _ sxpf.Environment, args []sxpf.Object) (sxpf.Object, error)

Call the builtin function.

func (BuiltinA) IsAtom 

func (b BuiltinA) IsAtom() bool

func (BuiltinA) IsEql 

func (b BuiltinA) IsEql(other sxpf.Object) bool

func (BuiltinA) IsEqual 

func (b BuiltinA) IsEqual(other sxpf.Object) bool

func (BuiltinA) IsNil 

func (b BuiltinA) IsNil() bool

func (BuiltinA) Name 

func (b BuiltinA) Name(eng *Engine) string

func (BuiltinA) Print 

func (b BuiltinA) Print(w io.Writer) (int, error)

func (BuiltinA) Repr 

func (b BuiltinA) Repr() string

func (BuiltinA) String 

func (b BuiltinA) String() string

type BuiltinCallExpr 

type BuiltinCallExpr struct {
	Proc Builtin
	Args []Expr
}

BuiltinCallExpr calls a builtin and returns the resulting object. It is an optimization of `CallExpr.`

func (*BuiltinCallExpr) Compute 

func (bce *BuiltinCallExpr) Compute(eng *Engine, env sxpf.Environment) (sxpf.Object, error)

func (*BuiltinCallExpr) String 

func (bce *BuiltinCallExpr) String() string

type BuiltinEEA 

type BuiltinEEA func(*Engine, sxpf.Environment, []sxpf.Object) (sxpf.Object, error)

BuiltinEEA is the signature of builtin functions that use all information, engine, environment, and arguments.

func (BuiltinEEA) Call 

func (b BuiltinEEA) Call(eng *Engine, env sxpf.Environment, args []sxpf.Object) (sxpf.Object, error)

Call the builtin function.

func (BuiltinEEA) IsAtom 

func (b BuiltinEEA) IsAtom() bool

func (BuiltinEEA) IsEql 

func (b BuiltinEEA) IsEql(other sxpf.Object) bool

func (BuiltinEEA) IsEqual 

func (b BuiltinEEA) IsEqual(other sxpf.Object) bool

func (BuiltinEEA) IsNil 

func (b BuiltinEEA) IsNil() bool

func (BuiltinEEA) Name 

func (b BuiltinEEA) Name(eng *Engine) string

func (BuiltinEEA) Print 

func (b BuiltinEEA) Print(w io.Writer) (int, error)

func (BuiltinEEA) Repr 

func (b BuiltinEEA) Repr() string

func (BuiltinEEA) String 

func (b BuiltinEEA) String() string

type CallError 

type CallError struct {
	Name string
	Err  error
}

CallError encapsulate an error that occured during a call.

func (CallError) Error 

func (e CallError) Error() string

func (CallError) Unwrap 

func (e CallError) Unwrap() error

type CallExpr 

type CallExpr struct {
	Proc Expr
	Args []Expr
}

CallExpr calls a procedure and returns the resulting objects.

func (*CallExpr) Compute 

func (ce *CallExpr) Compute(eng *Engine, env sxpf.Environment) (sxpf.Object, error)

func (*CallExpr) String 

func (ce *CallExpr) String() string

type Callable 

type Callable interface {
	// Call the value with the given args and environment.
	Call(*Engine, sxpf.Environment, []sxpf.Object) (sxpf.Object, error)
}

Callable is a value that can be called for evaluation.

func GetCallable 

func GetCallable(obj sxpf.Object) (Callable, bool)

GetCallable returns the object as a Callable, if possible.

type Engine 

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

Engine is the collection of all relevant data element to execute / evaluate an object.

func MakeEngine 

func MakeEngine(sf sxpf.SymbolFactory, root sxpf.Environment, parser Parser, executor Executor) *Engine

MakeEngine creates a new engine.

func (*Engine) Bind 

func (eng *Engine) Bind(name string, obj sxpf.Object) error

Bind a given object to a symbol of the given name in the engine's root environment.

func (*Engine) BindBuiltinA 

func (eng *Engine) BindBuiltinA(name string, fn BuiltinA) error

BindBuiltinA binds a standard builtin function to the given name in the engine's root environment.

func (*Engine) BindBuiltinEEA 

func (eng *Engine) BindBuiltinEEA(name string, fn BuiltinEEA) error

BindBuiltinEEA binds a special builtin function to the given name in the engine's root environment.

func (*Engine) BindSyntax 

func (eng *Engine) BindSyntax(name string, fn SyntaxFn) error

BindSyntax binds a syntax parser to the given name in the engine's root environment. It also binds the parser to the symbol directly.

func (*Engine) BuiltinName 

func (eng *Engine) BuiltinName(b Builtin) string

BuiltinName returns the name of the given Builtin.

func (*Engine) Call 

func (eng *Engine) Call(env sxpf.Environment, fn Callable, args []sxpf.Object) (sxpf.Object, error)

func (*Engine) Eval 

func (eng *Engine) Eval(env sxpf.Environment, obj sxpf.Object) (sxpf.Object, error)

Eval parses the given object and executes it in the environment.

func (*Engine) Execute 

func (eng *Engine) Execute(env sxpf.Environment, expr Expr) (sxpf.Object, error)

Execute the given expression in the given environment.

func (*Engine) ExecuteTCO 

func (eng *Engine) ExecuteTCO(env sxpf.Environment, expr Expr) (sxpf.Object, error)

ExecuteTCO the given expression in the given environment, but tail-call optimized.

func (*Engine) GetToplevelEnv 

func (eng *Engine) GetToplevelEnv() sxpf.Environment

GetToplevelEnv returns the current top-level environment.

func (*Engine) Parse 

func (eng *Engine) Parse(env sxpf.Environment, obj sxpf.Object) (Expr, error)

Parse the given object in the given environment.

func (*Engine) RootEnvironment 

func (eng *Engine) RootEnvironment() sxpf.Environment

RootEnvironment returns the root environment of the engine.

func (*Engine) SetToplevelEnv 

func (eng *Engine) SetToplevelEnv(env sxpf.Environment) error

SetToplevelEnv sets the given environment as the top-level environment. It must be the root environment or a child of it.

func (*Engine) SymbolFactory 

func (eng *Engine) SymbolFactory() sxpf.SymbolFactory

SymbolFactory returns the symbol factory of the engine.

type Executor 

type Executor interface {
	// Execute the expression in an environment and return the result.
	// It may have side-effects, on the given environment, or on the
	// general environment of the system.
	Execute(*Engine, sxpf.Environment, Expr) (sxpf.Object, error)
}

Executor is about controlling the execution of expressions. Do not call the method `Expr.Execute` directly, call the executor to do this.

func MakeSimpleExecutor 

func MakeSimpleExecutor() Executor

MakeSimpleExecutor creates a new executor which just executes expressions.

type Expr 

type Expr interface {
	// Compute the expression in an environment and return the result.
	// It may have side-effects, on the given environment, or on the
	// general environment of the system.
	Compute(*Engine, sxpf.Environment) (sxpf.Object, error)
}

Expr are values that are executed for evaluation in an environment.

type NotBoundError 

type NotBoundError struct {
	Env sxpf.Environment
	Sym *sxpf.Symbol
}

NotBoundError signals that a symbol was not found in an environment.

func (NotBoundError) Error 

func (e NotBoundError) Error() string

type NotCallableError 

type NotCallableError struct {
	Obj sxpf.Object
}

NotCallableError signals that a value cannot be called when it must be called.

func (NotCallableError) Error 

func (e NotCallableError) Error() string

func (NotCallableError) String 

func (e NotCallableError) String() string

type Parser 

type Parser interface {
	Parse(*Engine, sxpf.Environment, sxpf.Object) (Expr, error)
}

Parser transform an object into an executable expression.

func MakeDefaultParser 

func MakeDefaultParser() Parser

MakeDefaultParser creates a new default parser.

type ResolveExpr 

type ResolveExpr struct {
	Symbol *sxpf.Symbol
}

ResolveExpr resolves the given symbol in an environment and returns the value.

func (ResolveExpr) Compute 

func (re ResolveExpr) Compute(_ *Engine, env sxpf.Environment) (sxpf.Object, error)

type SelfExpr 

type SelfExpr struct {
	Obj sxpf.Object
}

SelfExpr returns the stored object.

func (SelfExpr) Compute 

func (se SelfExpr) Compute(*Engine, sxpf.Environment) (sxpf.Object, error)

type Syntax 

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

Syntax represents all syntax constructing functions implemented in Go.

func GetSyntax 

func GetSyntax(obj sxpf.Object) (*Syntax, bool)

GetSyntax returns the object as a syntax value if possible.

func MakeSyntax 

func MakeSyntax(name string, fn SyntaxFn) *Syntax

MakeSyntax creates a new special function.

func (*Syntax) IsAtom 

func (sy *Syntax) IsAtom() bool

func (*Syntax) IsEql 

func (sy *Syntax) IsEql(other sxpf.Object) bool

func (*Syntax) IsEqual 

func (sy *Syntax) IsEqual(other sxpf.Object) bool

func (*Syntax) IsNil 

func (sy *Syntax) IsNil() bool

func (*Syntax) Parse 

func (sy *Syntax) Parse(eng *Engine, env sxpf.Environment, args *sxpf.List) (Expr, error)

Parse the args by calling the syntax function.

func (*Syntax) Print 

func (sy *Syntax) Print(w io.Writer) (int, error)

func (*Syntax) Repr 

func (sy *Syntax) Repr() string

func (*Syntax) String 

func (sy *Syntax) String() string

type SyntaxFn 

type SyntaxFn func(*Engine, sxpf.Environment, *sxpf.List) (Expr, error)

SpecialFn is the signature of all syntax constructing functions.

Source Files

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