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fn.go
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fn.go
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package runtime
import (
"errors"
"fmt"
"github.com/glojurelang/glojure/pkg/ast"
"github.com/glojurelang/glojure/pkg/lang"
)
type Fn struct {
meta lang.IPersistentMap
astNode *ast.Node
env lang.Environment
}
var (
_ lang.IObj = (*Fn)(nil)
)
func NewFn(astNode *ast.Node, env lang.Environment) *Fn {
return &Fn{astNode: astNode, env: env}
}
func (fn *Fn) Meta() lang.IPersistentMap {
return fn.meta
}
func (fn *Fn) WithMeta(meta lang.IPersistentMap) interface{} {
cpy := *fn
cpy.meta = meta
return &cpy
}
func (fn *Fn) Invoke(args ...interface{}) interface{} {
fnNode := fn.astNode.Sub.(*ast.FnNode)
methods := fnNode.Methods
variadic := fnNode.IsVariadic
maxArity := fnNode.MaxFixedArity
if !variadic && len(args) > maxArity {
panic(lang.NewIllegalArgumentError(fmt.Sprintf("too many arguments (%d)", len(args))))
}
method, err := fn.findMethod(methods, args)
if err != nil {
panic(err)
}
fnEnv := fn.env.PushScope()
if fnNode.Local != nil {
localNode := fnNode.Local.Sub.(*ast.BindingNode)
fnEnv.BindLocal(localNode.Name, fn)
}
methodNode := method.Sub.(*ast.FnMethodNode)
fixedArity := methodNode.FixedArity
methodVariadic := methodNode.IsVariadic
body := methodNode.Body
bindingValues := args[:fixedArity]
arity := fixedArity
var bindingRestValue interface{}
if len(args) > len(bindingValues) {
arity++
bindingRestValue = lang.NewList(args[len(bindingValues):]...)
}
Recur:
params := methodNode.Params
for i, paramValue := range bindingValues {
param := params[i]
paramNode := param.Sub.(*ast.BindingNode)
fnEnv.BindLocal(paramNode.Name, paramValue)
}
if bindingRestValue != nil {
param := params[len(params)-1]
paramNode := param.Sub.(*ast.BindingNode)
fnEnv.BindLocal(paramNode.Name, bindingRestValue)
} else if methodVariadic {
param := params[len(params)-1]
paramNode := param.Sub.(*ast.BindingNode)
fnEnv.BindLocal(paramNode.Name, nil)
}
rt := lang.NewRecurTarget()
recurEnv := fnEnv.WithRecurTarget(rt)
recurErr := &lang.RecurError{Target: rt}
res, err := recurEnv.EvalAST(body)
if errors.As(err, &recurErr) {
if len(recurErr.Args) != arity {
panic("wrong number of arguments to recur")
}
bindingRestValue = nil
bindingValues = recurErr.Args[:fixedArity]
if len(recurErr.Args) > fixedArity {
bindingRestValue = recurErr.Args[fixedArity]
}
goto Recur
}
if err != nil {
panic(errorWithStack(err, lang.StackFrame{})) // TODO: think through error stacks
}
return res
}
func (fn *Fn) findMethod(methods []*ast.Node, args []interface{}) (*ast.Node, error) {
var variadicMethod *ast.Node
for _, method := range methods {
methodNode := method.Sub.(*ast.FnMethodNode)
if methodNode.IsVariadic {
variadicMethod = method
continue
}
if methodNode.FixedArity == len(args) {
return method, nil
}
}
if variadicMethod == nil || len(args) < variadicMethod.Sub.(*ast.FnMethodNode).FixedArity {
return nil, lang.NewIllegalArgumentError(fmt.Sprintf("wrong number of arguments (%d)", len(args)))
}
return variadicMethod, nil
}
func (fn *Fn) ApplyTo(args lang.ISeq) interface{} {
return fn.Invoke(seqToSlice(args)...)
}
func errorWithStack(err error, stackFrame lang.StackFrame) error {
if err == nil {
return nil
}
valErr, ok := err.(*lang.Error)
if !ok {
return lang.NewError(stackFrame, err)
}
return valErr.AddStack(stackFrame)
}