cb_unit.go

/*
 Copyright 2024 The XGo Authors (xgo.dev)
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
     http://www.apache.org/licenses/LICENSE-2.0
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
*/

package gogen

import (
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"log"
	"strconv"
	"strings"

	"github.com/goplus/gogen/target"
)

// ----------------------------------------------------------------------------

type objectID struct {
	pkg  string
	name string
}

type typeUnits = map[string]constant.Value

// const XGou_XXX = "mm=1,cm=10,dm=100,m=1000"
func (p *Package) buildTypeUnits(id objectID, tok token.Token) (ret typeUnits, ok bool) {
	v, ok := p.lookupTypeUnitsVal(id)
	if ok {
		units := strings.Split(v, ",")
		ret = make(typeUnits, len(units))
		for _, unit := range units {
			if pos := strings.Index(unit, "="); pos > 0 {
				ret[unit[:pos]] = constant.MakeFromLiteral(unit[pos+1:], tok, 0)
			}
		}
	}
	return
}

/*
"ns": time.Nanosecond,
"us": time.Microsecond,
"µs": time.Microsecond,
"ms": time.Millisecond,
"s":  time.Second,
"m":  time.Minute,
"h":  time.Hour,
"d":  24 * time.Hour,
*/
func (p *Package) lookupTypeUnitsVal(id objectID) (string, bool) {
	if id.name == "Duration" && id.pkg == "time" { // time.Duration
		const tv = "ns=1,us=1000,µs=1000,ms=1000000,s=1000000000,m=60000000000,h=3600000000000,d=86400000000000"
		return tv, true
	}
	imp := p.Import(id.pkg)
	if ounits := imp.TryRef("XGou_" + id.name); ounits != nil {
		if v := ounits.(*types.Const).Val(); v.Kind() == constant.String {
			return constant.StringVal(v), true
		}
	}
	return "", false
}

// ----------------------------------------------------------------------------

type unitMgr struct {
	units map[objectID]typeUnits
}

func (p *unitMgr) init() {
	units := make(map[objectID]typeUnits)
	p.units = units
}

func (p *Package) getUnits(id objectID, tok token.Token) (units typeUnits, ok bool) {
	units, ok = p.units[id]
	if !ok {
		if units, ok = p.buildTypeUnits(id, tok); ok {
			p.units[id] = units
		}
	}
	return
}

func getUnits(pkg *Package, ot *types.TypeName) (id objectID, units typeUnits, ok bool) {
	id = objectID{ot.Pkg().Path(), ot.Name()}
	units, ok = pkg.getUnits(id, token.FLOAT)
	return
}

// ----------------------------------------------------------------------------

// ValWithUnit func
func (p *CodeBuilder) ValWithUnit(v *ast.BasicLit, t types.Type, unit string) *CodeBuilder {
	if debugInstr {
		log.Println("ValWithUnit", v.Value, t, unit)
	}
	var id objectID
	var units typeUnits
	var found bool
	pkg := p.pkg
	if alias, ok := t.(*types.Alias); ok {
		if id, units, found = getUnits(pkg, alias.Obj()); !found {
			t = types.Unalias(t)
		}
	}
	if !found {
		named, ok := t.(*types.Named)
		if !ok {
			panicUnitErr(p, v, unit, "literal with unit cannot be used: `%v` is not a named type", t)
		}
		id, units, found = getUnits(pkg, named.Obj())
		if !found {
			panicUnitErr(p, v, unit, "literal with unit cannot be used: no units of `%s.%s` found", id.pkg, id.name)
		}
	}
	u, ok := units[unit]
	if !ok {
		panicUnitErr(p, v, unit, "literal with unit: unknown unit `%s` for `%s.%s`", unit, id.pkg, id.name)
	}
	e := toExpr(pkg, v, v)
	val := constant.BinaryOp(e.CVal, token.MUL, u)
	e.CVal = val
	if isFloat(t) {
		e.Val = &target.BasicLit{Kind: token.FLOAT, Value: floatVal(val)}
	} else {
		e.Val = &target.BasicLit{Kind: token.INT, Value: val.ExactString()}
	}
	e.Type = t
	p.Val(e, v)
	return p
}

func panicUnitErr(cb *CodeBuilder, v *ast.BasicLit, unit, format string, args ...any) {
	cb.panicCodeErrorf(v.Pos(), v.End()+token.Pos(len(unit)), format, args...)
}

func isFloat(t types.Type) bool {
	switch t := t.Underlying().(type) {
	case *types.Basic:
		return t.Info()&types.IsFloat != 0
	}
	return false
}

func floatVal(val constant.Value) string {
	f, _ := constant.Float64Val(val)
	return strconv.FormatFloat(f, 'g', -1, 64)
}

// ----------------------------------------------------------------------------