zen/core/zcaller/zcaller.go

package zcaller

import (
	"log/slog"
	"os"
	"runtime"
	"strings"
)

// Current returns the ProgramCounter of the caller.
//
// It gives information about the function that called
// this.
//
// Returns 0 if caller information is not available.
func Current() uintptr {
	return Get(3)
}

// Get works just like Current, but it allows you to
// specify the number of frames to skip.
//
// For reference, current is equivalent to Get(3).
// (use Get(2) because Current wraps this function and has to add +1 to the skip value)
//
// Returns 0 if caller information is not available.
func Get(skip int) uintptr {
	pcs := make([]uintptr, 1)
	n := runtime.Callers(skip, pcs)
	if n == 0 {
		return 0
	}
	return pcs[0]
}

// Frame creates a runtime.Frame from a ProgramCounter.
//
// Return zero value if the frame is not available.
func Frame(pc uintptr) runtime.Frame {
	frames := runtime.CallersFrames([]uintptr{pc})
	frame, _ := frames.Next()
	return frame
}

// Caller represents the caller of a function.
//
// It gives helper methods to get the caller's information.
type Caller uintptr

func (ca Caller) LogValue() slog.Value {
	if ca == 0 {
		return slog.AnyValue(nil)
	}

	return ca.Frame().LogValue()
}

func (ca Caller) Frame() RuntimeFrame {
	return RuntimeFrame{Frame(uintptr(ca))}
}

type RuntimeFrame struct {
	runtime.Frame
}

func (ru RuntimeFrame) LogValue() slog.Value {
	return slog.GroupValue(
		slog.String("file", ru.ShortFile()),
		slog.Int("line", ru.Line),
		slog.String("function", ru.ShortFunction()),
	)
}

func (f RuntimeFrame) ShortFile() string {
	wd, err := os.Getwd()
	if err != nil {
		return f.File
	}
	if after, found := strings.CutPrefix(f.File, wd); found {
		return strings.TrimPrefix(after, string(os.PathSeparator))
	}
	return f.File
}

func (f RuntimeFrame) ShortFunction() string {
	split := strings.Split(f.Function, string(os.PathSeparator))
	return split[len(split)-1]
}