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https://github.com/golang/go
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c85f9fa958
This might not be necessary after we fix handling for line directives, but it's always better to avoid the panic here. Updates golang/go#34433 Change-Id: Ica4fb571dff6753fb15bf8d397c55f713284aa27 Reviewed-on: https://go-review.googlesource.com/c/tools/+/196662 Run-TryBot: Rebecca Stambler <rstambler@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Cottrell <iancottrell@google.com>
95 lines
2.9 KiB
Go
95 lines
2.9 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package span
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import (
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"fmt"
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"unicode/utf16"
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"unicode/utf8"
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)
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// ToUTF16Column calculates the utf16 column expressed by the point given the
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// supplied file contents.
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// This is used to convert from the native (always in bytes) column
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// representation and the utf16 counts used by some editors.
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func ToUTF16Column(p Point, content []byte) (int, error) {
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if content == nil {
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return -1, fmt.Errorf("ToUTF16Column: missing content")
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}
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if !p.HasPosition() {
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return -1, fmt.Errorf("ToUTF16Column: point is missing position")
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}
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if !p.HasOffset() {
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return -1, fmt.Errorf("ToUTF16Column: point is missing offset")
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}
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offset := p.Offset() // 0-based
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colZero := p.Column() - 1 // 0-based
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if colZero == 0 {
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// 0-based column 0, so it must be chr 1
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return 1, nil
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} else if colZero < 0 {
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return -1, fmt.Errorf("ToUTF16Column: column is invalid (%v)", colZero)
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}
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// work out the offset at the start of the line using the column
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lineOffset := offset - colZero
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if lineOffset < 0 || offset > len(content) {
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return -1, fmt.Errorf("ToUTF16Column: offsets %v-%v outside file contents (%v)", lineOffset, offset, len(content))
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}
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// Use the offset to pick out the line start.
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// This cannot panic: offset > len(content) and lineOffset < offset.
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start := content[lineOffset:]
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// Now, truncate down to the supplied column.
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start = start[:colZero]
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// and count the number of utf16 characters
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// in theory we could do this by hand more efficiently...
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return len(utf16.Encode([]rune(string(start)))) + 1, nil
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}
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// FromUTF16Column advances the point by the utf16 character offset given the
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// supplied line contents.
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// This is used to convert from the utf16 counts used by some editors to the
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// native (always in bytes) column representation.
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func FromUTF16Column(p Point, chr int, content []byte) (Point, error) {
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if !p.HasOffset() {
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return Point{}, fmt.Errorf("FromUTF16Column: point is missing offset")
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}
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// if chr is 1 then no adjustment needed
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if chr <= 1 {
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return p, nil
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}
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if p.Offset() >= len(content) {
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return p, fmt.Errorf("FromUTF16Column: offset (%v) greater than length of content (%v)", p.Offset(), len(content))
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}
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remains := content[p.Offset():]
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// scan forward the specified number of characters
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for count := 1; count < chr; count++ {
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if len(remains) <= 0 {
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return Point{}, fmt.Errorf("FromUTF16Column: chr goes beyond the content")
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}
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r, w := utf8.DecodeRune(remains)
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if r == '\n' {
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// Per the LSP spec:
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//
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// > If the character value is greater than the line length it
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// > defaults back to the line length.
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break
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}
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remains = remains[w:]
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if r >= 0x10000 {
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// a two point rune
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count++
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// if we finished in a two point rune, do not advance past the first
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if count >= chr {
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break
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}
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}
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p.v.Column += w
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p.v.Offset += w
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}
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return p, nil
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}
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