glisp/s-array.go at master · qjpcpu/glisp · GitHub

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package glisp

import (
	"errors"
	"fmt"
	"strings"
)

type SexpArray []Sexp

func (arr SexpArray) SexpString() string {
	var out strings.Builder
	out.WriteByte('[')
	for i, expr := range arr {
		if i > 0 {
			out.WriteByte(' ')
		}
		out.WriteString(expr.SexpString())
	}
	out.WriteByte(']')
	return out.String()
}

func MapArray(env *Environment, fun *SexpFunction, arr SexpArray) (SexpArray, error) {
	result := make([]Sexp, len(arr))
	var err error

	for i := range arr {
		result[i], err = env.Apply(fun, MakeArgs(arr[i:i+1]...))
		if err != nil {
			return SexpArray(result), err
		}
	}

	return SexpArray(result), nil
}

func FlatMapArray(env *Environment, fun *SexpFunction, arr SexpArray) (SexpArray, error) {
	result := make([]Sexp, 0, len(arr))

	for i := range arr {
		res, err := env.Apply(fun, MakeArgs(arr[i:i+1]...))
		if err != nil {
			return SexpArray(result), err
		}
		if res == SexpNull {
			continue
		}
		if !IsArray(res) {
			return SexpArray(result), errors.New("flatmap function must return array")
		}
		arr := res.(SexpArray)
		result = append(result, arr...)
	}

	return SexpArray(result), nil
}

func FilterArray(env *Environment, fun *SexpFunction, arr SexpArray) (SexpArray, error) {
	result := make([]Sexp, 0, len(arr))

	for i := range arr {
		item := arr[i]
		ret, err := env.Apply(fun, MakeArgs(item))
		if err != nil {
			return SexpArray(result), err
		}
		pass, ok := ret.(SexpBool)
		if !ok {
			return SexpArray{}, errors.New("filter function must return boolean")
		} else if pass {
			result = append(result, item)
		}
	}

	return SexpArray(result), nil
}

func ConcatArray(arr SexpArray, exprs Args) (SexpArray, error) {
	ret := make(SexpArray, len(arr))
	copy(ret, arr)
	var err error
	exprs.Foreach(func(expr Sexp) bool {
		switch t := expr.(type) {
		case SexpArray:
			ret = append(ret, t...)
		default:
			err = fmt.Errorf("second argument(%s) is not an array", InspectType(expr))
		}
		return err == nil
	})
	if err != nil {
		return arr, err
	}

	return ret, nil
}

func FoldlArray(env *Environment, fun *SexpFunction, lst Sexp, acc Sexp) (Sexp, error) {
	if lst == SexpNull {
		return acc, nil
	}
	var list SexpArray
	switch e := lst.(type) {
	case SexpArray:
		list = e
	default:
		return SexpNull, errors.New("not a array")
	}

	for _, item := range list {
		var err error
		acc, err = env.Apply(fun, MakeArgs(item, acc))
		if err != nil {
			return SexpNull, err
		}
	}
	return acc, nil
}