text/expander-context.go

// expander-context.go
package text

import (
	"errors"
	"fmt"
	"strconv"
	"strings"

	"portale-stac.it/packages/golang"
)

const varIntro = '$'

type ExpanderFunc func(ctx ExpanderContext, varValue string, args []string) (result string, err error)

type ExpanderFuncBlock struct {
	name        string
	expFunc     ExpanderFunc
	minArgs     int
	maxArgs     int
	description string
}

func (self *ExpanderFuncBlock) CheckNumArgs(n int) (ok bool) {
	ok = (self.minArgs < 0 || n >= self.minArgs) && (self.maxArgs < 0 || n <= self.maxArgs)
	return
}

func (self *ExpanderFuncBlock) synopsys(sb *strings.Builder) {
	if self.minArgs < 0 && self.maxArgs < 0 {
		sb.WriteString("[...]")
	} else {
		var i int
		for i = 0; i < self.minArgs; i++ {
			if i > 0 {
				sb.WriteByte(' ')
			}
			sb.WriteString("arg")
			sb.WriteString(strconv.Itoa(i + 1))
		}
		if self.maxArgs < 0 {
			sb.WriteString("...")
		} else if i < self.maxArgs {
			for j := i; j < self.maxArgs; j++ {
				if j > 0 {
					sb.WriteByte(' ')
				}
				sb.WriteString("[arg")
				sb.WriteString(strconv.Itoa(j + 1))
			}
			for j := i; j < self.maxArgs; j++ {
				sb.WriteByte(']')
			}
		}
	}
}

func (self *ExpanderFuncBlock) String() string {
	var sb strings.Builder
	sb.WriteString(self.name)
	sb.WriteByte(' ')
	self.synopsys(&sb)
	if len(self.description) > 0 {
		sb.WriteString(" -- ")
		if len(self.description) > 80 {
			sb.WriteString(self.description[0:80])
			sb.WriteString("...")
		} else {
			sb.WriteString(self.description)
		}
	}
	return sb.String()
}

type ExpanderContext interface {
	VariableHandler
	GetFunc(name string) (f ExpanderFunc, err error)
	AddFunc(name string, f ExpanderFunc, minArgs, maxArgs int, description string)
	GetVar(name string) (value string, exists bool)
	SetVar(name string, value string) (repeatedValue string)
}

type BaseExpander struct {
	functions map[string]*ExpanderFuncBlock
}

func (self *BaseExpander) GetVar(name string) (value string, exists bool) {
	return
}

func (self *BaseExpander) SetVar(name string, value string) (repeatedValue string) {
	return value
}

func NewExpander() *BaseExpander {
	return &BaseExpander{
		functions: make(map[string]*ExpanderFuncBlock),
	}
}

func (self *BaseExpander) Init() {
	if self.functions == nil {
		self.functions = make(map[string]*ExpanderFuncBlock)
	}
}

func (self *BaseExpander) GetFunc(name string) (f ExpanderFunc, err error) {
	var ok bool
	var info *ExpanderFuncBlock
	if info, ok = self.functions[name]; !ok {
		err = fmt.Errorf("unknown function %q", name)
	} else {
		f = info.expFunc
	}
	return
}

func (self *BaseExpander) AddFunc(name string, f ExpanderFunc, minArgs, maxArgs int, description string) {
	self.functions[name] = &ExpanderFuncBlock{
		name:        name,
		expFunc:     f,
		minArgs:     minArgs,
		maxArgs:     maxArgs,
		description: description,
	}
}

func (self *BaseExpander) Handle(varSpec string, flags ScannerFlag) (value string, err error) {
	err = errors.New("maybe you did somwthing wrong")
	return
}

func (self *BaseExpander) IterateFunc(op func(funcInfo *ExpanderFuncBlock) (err error)) (err error) {
	if op != nil {
		err = golang.IterateSortedMap(self.functions, func(key string, info *ExpanderFuncBlock) error {
			return op(info)
		})
	}
	return
}