// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package objabi

import "strings"

// PathToPrefix converts raw string to the prefix that will be used in the
// symbol table. All control characters, space, '%' and '"', as well as
// non-7-bit clean bytes turn into %xx. The period needs escaping only in the
// last segment of the path, and it makes for happier users if we escape that as
// little as possible.
func PathToPrefix(s string) string {
	slash := strings.LastIndex(s, "/")
	// check for chars that need escaping
	n := 0
	for r := 0; r < len(s); r++ {
		if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F {
			n++
		}
	}

	// quick exit
	if n == 0 {
		return s
	}

	// escape
	const hex = "0123456789abcdef"
	p := make([]byte, 0, len(s)+2*n)
	for r := 0; r < len(s); r++ {
		if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F {
			p = append(p, '%', hex[c>>4], hex[c&0xF])
		} else {
			p = append(p, c)
		}
	}

	return string(p)
}

// IsRuntimePackagePath examines 'pkgpath' and returns TRUE if it
// belongs to the collection of "runtime-related" packages, including
// "runtime" itself, "reflect", "syscall", and the
// "runtime/internal/*" packages. The compiler and/or assembler in
// some cases need to be aware of when they are building such a
// package, for example to enable features such as ABI selectors in
// assembly sources.
//
// Keep in sync with cmd/dist/build.go:IsRuntimePackagePath.
func IsRuntimePackagePath(pkgpath string) bool {
	rval := false
	switch pkgpath {
	case "runtime":
		rval = true
	case "reflect":
		rval = true
	case "syscall":
		rval = true
	case "internal/bytealg":
		rval = true
	default:
		rval = strings.HasPrefix(pkgpath, "runtime/internal")
	}
	return rval
}