utils.go

package main

import (
	"bytes"
	"github.com/nsf/tulib"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"unicode"
	"unicode/utf8"
)

var invisible_rune_table = []rune{
	'@',  // 0
	'A',  // 1
	'B',  // 2
	'C',  // 3
	'D',  // 4
	'E',  // 5
	'F',  // 6
	'G',  // 7
	'H',  // 8
	'I',  // 9
	'J',  // 10
	'K',  // 11
	'L',  // 12
	'M',  // 13
	'N',  // 14
	'O',  // 15
	'P',  // 16
	'Q',  // 17
	'R',  // 18
	'S',  // 19
	'T',  // 20
	'U',  // 21
	'V',  // 22
	'W',  // 23
	'X',  // 24
	'Y',  // 25
	'Z',  // 26
	'[',  // 27
	'\\', // 28
	']',  // 29
	'^',  // 30
	'_',  // 31
}

// somewhat close to what wcwidth does, except rune_width doesn't return 0 or
// -1, it's always 1 or 2
func rune_width(r rune) int {
	if r >= 0x1100 &&
		(r <= 0x115f || r == 0x2329 || r == 0x232a ||
			(r >= 0x2e80 && r <= 0xa4cf && r != 0x303f) ||
			(r >= 0xac00 && r <= 0xd7a3) ||
			(r >= 0xf900 && r <= 0xfaff) ||
			(r >= 0xfe30 && r <= 0xfe6f) ||
			(r >= 0xff00 && r <= 0xff60) ||
			(r >= 0xffe0 && r <= 0xffe6) ||
			(r >= 0x20000 && r <= 0x2fffd) ||
			(r >= 0x30000 && r <= 0x3fffd)) {
		return 2
	}
	return 1
}

func rune_advance_len(r rune, pos int) int {
	switch {
	case r == '\t':
		return tabstop_length - pos%tabstop_length
	case r < 32:
		// for invisible chars like ^R ^@ and such, two cells
		return 2
	}
	return rune_width(r)
}

func vlen(data []byte, pos int) int {
	origin := pos
	for len(data) > 0 {
		r, rlen := utf8.DecodeRune(data)
		data = data[rlen:]
		pos += rune_advance_len(r, pos)
	}
	return pos - origin
}

func iter_nonspace_words(data []byte, cb func(word []byte)) {
	for {
		for len(data) > 0 && is_space(data[0]) {
			data = data[1:]
		}

		if len(data) == 0 {
			return
		}

		i := 0
		for i < len(data) && !is_space(data[i]) {
			i += 1
		}
		cb(data[:i])
		data = data[i:]
	}
}

func iter_words(data []byte, cb func(word []byte)) {
	for {
		if len(data) == 0 {
			return
		}

		r, rlen := utf8.DecodeRune(data)
		// skip non-word runes
		for !is_word(r) {
			data = data[rlen:]
			if len(data) == 0 {
				return
			}
			r, rlen = utf8.DecodeRune(data)
		}

		// must be on a word rune
		i := 0
		for is_word(r) && i < len(data) {
			i += rlen
			r, rlen = utf8.DecodeRune(data[i:])
		}
		cb(data[:i])
		data = data[i:]
	}
}

func iter_words_backward(data []byte, cb func(word []byte)) {
	for {
		if len(data) == 0 {
			return
		}

		r, rlen := utf8.DecodeLastRune(data)
		// skip non-word runes
		for !is_word(r) {
			data = data[:len(data)-rlen]
			if len(data) == 0 {
				return
			}
			r, rlen = utf8.DecodeLastRune(data)
		}

		// must be on a word rune
		i := len(data)
		for is_word(r) && i > 0 {
			i -= rlen
			r, rlen = utf8.DecodeLastRune(data[:i])
		}
		cb(data[i:])
		data = data[:i]
	}
}

func readdir_stat(dir string, f *os.File) ([]os.FileInfo, error) {
	names, err := f.Readdirnames(-1)
	if err != nil {
		return nil, err
	}

	fis := make([]os.FileInfo, 0, len(names))
	for _, name := range names {
		fi, err := os.Stat(filepath.Join(dir, name))
		if err != nil {
			continue
		}
		fis = append(fis, fi)
	}
	return fis, nil
}

func index_first_non_space(s []byte) int {
	for i := 0; i < len(s); i++ {
		if s[i] != '\t' && s[i] != ' ' {
			return i
		}
	}
	return len(s)
}

func index_last_non_space(s []byte) int {
	for i := len(s) - 1; i >= 0; i-- {
		if s[i] != '\t' && s[i] != ' ' {
			return i
		}
	}
	return -1
}

func abs_path(filename string) string {
	path, err := filepath.Abs(filename)
	if err != nil {
		panic(err)
	}
	return path
}

func grow_byte_slice(s []byte, desired_cap int) []byte {
	if cap(s) < desired_cap {
		ns := make([]byte, len(s), desired_cap)
		copy(ns, s)
		return ns
	}
	return s
}

func insert_bytes(s []byte, offset int, data []byte) []byte {
	n := len(s) + len(data)
	s = grow_byte_slice(s, n)
	s = s[:n]
	copy(s[offset+len(data):], s[offset:])
	copy(s[offset:], data)
	return s
}

func copy_byte_slice(dst, src []byte) []byte {
	if cap(dst) < len(src) {
		dst = clone_byte_slice(src)
	}
	dst = dst[:len(src)]
	copy(dst, src)
	return dst
}

func clone_byte_slice(s []byte) []byte {
	c := make([]byte, len(s))
	copy(c, s)
	return c
}

// assumes the same line and a.boffset < b.offset order
func bytes_between(a, b cursor_location) []byte {
	return a.line.data[a.boffset:b.boffset]
}

func is_word(r rune) bool {
	return r == '_' || unicode.IsLetter(r) || unicode.IsNumber(r)
}

func is_space(b byte) bool {
	return b == ' ' || b == '\t' || b == '\n'
}

func find_place_for_rect(win, pref tulib.Rect) tulib.Rect {
	var vars [4]tulib.Rect

	vars[0] = pref.Intersection(win)
	if vars[0] == pref {
		// this is just a common path, everything fits in
		return pref
	}

	// If a rect doesn't fit in the window, try to select the most
	// optimal position amongst mirrored variants.

	// invert X
	vars[1] = pref
	vars[1].X = win.Width - pref.Width
	vars[1] = vars[1].Intersection(win)

	// invert Y
	vars[2] = pref
	vars[2].Y -= pref.Height + 1
	vars[2] = vars[2].Intersection(win)

	// invert X and Y
	vars[3] = pref
	vars[3].X = win.Width - pref.Width
	vars[3].Y -= pref.Height + 1
	vars[3] = vars[3].Intersection(win)

	optimal_i, optimal_w, optimal_h := 0, 0, 0
	// find optimal width
	for i := 0; i < 4; i++ {
		if vars[i].Width > optimal_w {
			optimal_w = vars[i].Width
		}
	}

	// find optimal height (amongst optimal widths) and its index
	for i := 0; i < 4; i++ {
		if vars[i].Width != optimal_w {
			continue
		}
		if vars[i].Height > optimal_h {
			optimal_h = vars[i].Height
			optimal_i = i
		}
	}
	return vars[optimal_i]
}

// Function will iterate 'data' contents, calling 'cb' on some data or on '\n',
// but never both. For example, given this data: "\n123\n123\n\n", it will call
// 'cb' 6 times: ['\n', '123', '\n', '123', '\n', '\n']
func iter_lines(data []byte, cb func([]byte)) {
	offset := 0
	for {
		if offset == len(data) {
			return
		}

		i := bytes.IndexByte(data[offset:], '\n')
		switch i {
		case -1:
			cb(data[offset:])
			return
		case 0:
			cb(data[offset : offset+1])
			offset++
			continue
		}

		cb(data[offset : offset+i])
		cb(data[offset+i : offset+i+1])
		offset += i + 1
	}
}

var double_comma = []byte(",,")

func split_double_csv(data []byte) (a, b []byte) {
	i := bytes.Index(data, double_comma)
	if i == -1 {
		return data, nil
	}

	return data[:i], data[i+2:]
}

type line_reader struct {
	data   []byte
	offset int
}

func new_line_reader(data []byte) line_reader {
	return line_reader{data, 0}
}

func (l *line_reader) read_line() []byte {
	data := l.data[l.offset:]
	i := bytes.Index(data, []byte{'\n'})
	if i == -1 {
		l.offset = len(l.data)
		return data
	}

	l.offset += i + 1
	return data[:i]
}

func atoi(data []byte) (int, error) {
	return strconv.Atoi(string(data))
}

func substitute_home(path string) string {
	if !strings.HasPrefix(path, "~") {
		return path
	}
	home := os.Getenv("HOME")
	if home == "" {
		panic("HOME is not set")
	}
	return filepath.Join(home, path[1:])
}

func substitute_symlinks(path string) string {
	if path == "" {
		return ""
	}
	after, err := filepath.EvalSymlinks(path)
	if err != nil {
		return path
	}

	if strings.HasSuffix(path, string(filepath.Separator)) {
		return after + string(filepath.Separator)
	}
	return after
}

func is_file_hidden(path string) bool {
	if path == "." || path == ".." {
		return true
	}

	if len(path) > 1 {
		if strings.HasPrefix(path, "./") {
			return false
		}
		if strings.HasPrefix(path, "..") {
			return false
		}
		if strings.HasPrefix(path, ".") {
			return true
		}
	}
	return false
}