96 lines
2.0 KiB
Go
96 lines
2.0 KiB
Go
|
package parse
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"io"
|
||
|
|
"strings"
|
||
|
|
"unicode"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Position returns the line and column number for a certain position in a file. It is useful for recovering the position in a file that caused an error.
|
||
|
|
// It only treates \n, \r, and \r\n as newlines, which might be different from some languages also recognizing \f, \u2028, and \u2029 to be newlines.
|
||
|
|
func Position(r io.Reader, offset int) (line, col int, context string) {
|
||
|
|
l := NewInput(r)
|
||
|
|
line = 1
|
||
|
|
for l.Pos() < offset {
|
||
|
|
c := l.Peek(0)
|
||
|
|
n := 1
|
||
|
|
newline := false
|
||
|
|
if c == '\n' {
|
||
|
|
newline = true
|
||
|
|
} else if c == '\r' {
|
||
|
|
if l.Peek(1) == '\n' {
|
||
|
|
newline = true
|
||
|
|
n = 2
|
||
|
|
} else {
|
||
|
|
newline = true
|
||
|
|
}
|
||
|
|
} else if c >= 0xC0 {
|
||
|
|
var r rune
|
||
|
|
if r, n = l.PeekRune(0); r == '\u2028' || r == '\u2029' {
|
||
|
|
newline = true
|
||
|
|
}
|
||
|
|
} else if c == 0 && l.Err() != nil {
|
||
|
|
break
|
||
|
|
}
|
||
|
|
|
||
|
|
if 1 < n && offset < l.Pos()+n {
|
||
|
|
break
|
||
|
|
}
|
||
|
|
l.Move(n)
|
||
|
|
|
||
|
|
if newline {
|
||
|
|
line++
|
||
|
|
offset -= l.Pos()
|
||
|
|
l.Skip()
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
col = len([]rune(string(l.Lexeme()))) + 1
|
||
|
|
context = positionContext(l, line, col)
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
func positionContext(l *Input, line, col int) (context string) {
|
||
|
|
for {
|
||
|
|
c := l.Peek(0)
|
||
|
|
if c == 0 && l.Err() != nil || c == '\n' || c == '\r' {
|
||
|
|
break
|
||
|
|
}
|
||
|
|
l.Move(1)
|
||
|
|
}
|
||
|
|
rs := []rune(string(l.Lexeme()))
|
||
|
|
|
||
|
|
// cut off front or rear of context to stay between 60 characters
|
||
|
|
limit := 60
|
||
|
|
offset := 20
|
||
|
|
ellipsisFront := ""
|
||
|
|
ellipsisRear := ""
|
||
|
|
if limit < len(rs) {
|
||
|
|
if col <= limit-offset {
|
||
|
|
ellipsisRear = "..."
|
||
|
|
rs = rs[:limit-3]
|
||
|
|
} else if col >= len(rs)-offset-3 {
|
||
|
|
ellipsisFront = "..."
|
||
|
|
col -= len(rs) - offset - offset - 7
|
||
|
|
rs = rs[len(rs)-offset-offset-4:]
|
||
|
|
} else {
|
||
|
|
ellipsisFront = "..."
|
||
|
|
ellipsisRear = "..."
|
||
|
|
rs = rs[col-offset-1 : col+offset]
|
||
|
|
col = offset + 4
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// replace unprintable characters by a space
|
||
|
|
for i, r := range rs {
|
||
|
|
if !unicode.IsGraphic(r) {
|
||
|
|
rs[i] = '·'
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
context += fmt.Sprintf("%5d: %s%s%s\n", line, ellipsisFront, string(rs), ellipsisRear)
|
||
|
|
context += fmt.Sprintf("%s^", strings.Repeat(" ", 6+col))
|
||
|
|
return
|
||
|
|
}
|