clerk: internal/lsp/lsputil/lineindex.go (ab4f6083f493cb5911c86ae5f723d4519f7d52da)

1

package lsputil

2

3

import (

4

	"sort"

5

	"unicode/utf8"

6

7

	"go.lsp.dev/protocol"

8

9

	"olexsmir.xyz/clerk/journal/token"

10

11

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// LineIndex resolves byte offsets to LSP positions (and back) in O(log n) from

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// a precomputed table of line starts, avoiding a per-request content scan.

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type LineIndex struct {

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	content string

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	starts  []int // byte offset of each line's first byte; starts[0] == 0

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18

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// NewLineIndex builds the line-start table for content.

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func NewLineIndex(content string) *LineIndex {

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	starts := make([]int, 1, len(content)/20+1)

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	for i := 0; i < len(content); i++ {

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		if content[i] == '\n' {

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			starts = append(starts, i+1)

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26

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	return &LineIndex{content: content, starts: starts}

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// Position converts a byte offset to a 0-based LSP position.

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func (l *LineIndex) Position(offset int) protocol.Position {

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	if offset < 0 {

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		offset = 0

34

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	if offset > len(l.content) {

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		offset = len(l.content)

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	idx := sort.Search(len(l.starts), func(i int) bool { return l.starts[i] > offset }) - 1

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	lineStart := l.starts[idx]

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	return protocol.Position{

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		Line:      uint32(idx),

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		Character: uint32(Utf16Col(l.content[lineStart:offset], offset-lineStart)),

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// Offset converts a 0-based line and UTF-16 code unit column to a byte offset,

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// clamped to the content bounds. The inverse of Position; matches the

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// standalone Offset on the same content.

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func (l *LineIndex) Offset(line, col int) int {

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	if line < 0 {

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		line = 0

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	if line >= len(l.starts) {

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		return len(l.content)

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	lineStart := l.starts[line]

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	lineEnd := len(l.content)

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	if line+1 < len(l.starts) {

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		lineEnd = l.starts[line+1]

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	for lineEnd > lineStart && (l.content[lineEnd-1] == '\n' || l.content[lineEnd-1] == '\r') {

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		lineEnd--

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	off := lineStart

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	units := 0

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	for off < lineEnd && units < col {

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		r, size := utf8.DecodeRuneInString(l.content[off:lineEnd])

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		off += size

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		units += utf16Len(r)

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	return off

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// SpanRange converts a span to a protocol range, trimming trailing whitespace and newlines from the end.

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func (l *LineIndex) SpanRange(span token.Span) protocol.Range {

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	return protocol.Range{

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		Start: l.Position(span.Start.Offset),

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		End:   l.Position(l.clampEnd(span.End.Offset)),

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func (l *LineIndex) clampEnd(end int) int {

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	for end > 0 {

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		switch l.content[end-1] {

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		case ' ', '\t', '\r', '\n':

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			end--

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		default:

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			return end

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	return end

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1	package lsputil
2
3	import (
4	"sort"
5	"unicode/utf8"
6
7	"go.lsp.dev/protocol"
8
9	"olexsmir.xyz/clerk/journal/token"
10	)
11
12	// LineIndex resolves byte offsets to LSP positions (and back) in O(log n) from
13	// a precomputed table of line starts, avoiding a per-request content scan.
14	type LineIndex struct {
15	content string
16	starts []int // byte offset of each line's first byte; starts[0] == 0
17	}
18
19	// NewLineIndex builds the line-start table for content.
20	func NewLineIndex(content string) *LineIndex {
21	starts := make([]int, 1, len(content)/20+1)
22	for i := 0; i < len(content); i++ {
23	if content[i] == '\n' {
24	starts = append(starts, i+1)
25	}
26	}
27	return &LineIndex{content: content, starts: starts}
28	}
29
30	// Position converts a byte offset to a 0-based LSP position.
31	func (l *LineIndex) Position(offset int) protocol.Position {
32	if offset < 0 {
33	offset = 0
34	}
35	if offset > len(l.content) {
36	offset = len(l.content)
37	}
38	idx := sort.Search(len(l.starts), func(i int) bool { return l.starts[i] > offset }) - 1
39	lineStart := l.starts[idx]
40	return protocol.Position{
41	Line: uint32(idx),
42	Character: uint32(Utf16Col(l.content[lineStart:offset], offset-lineStart)),
43	}
44	}
45
46	// Offset converts a 0-based line and UTF-16 code unit column to a byte offset,
47	// clamped to the content bounds. The inverse of Position; matches the
48	// standalone Offset on the same content.
49	func (l *LineIndex) Offset(line, col int) int {
50	if line < 0 {
51	line = 0
52	}
53	if line >= len(l.starts) {
54	return len(l.content)
55	}
56	lineStart := l.starts[line]
57	lineEnd := len(l.content)
58	if line+1 < len(l.starts) {
59	lineEnd = l.starts[line+1]
60	}
61	for lineEnd > lineStart && (l.content[lineEnd-1] == '\n' \|\| l.content[lineEnd-1] == '\r') {
62	lineEnd--
63	}
64	off := lineStart
65	units := 0
66	for off < lineEnd && units < col {
67	r, size := utf8.DecodeRuneInString(l.content[off:lineEnd])
68	off += size
69	units += utf16Len(r)
70	}
71	return off
72	}
73
74	// SpanRange converts a span to a protocol range, trimming trailing whitespace and newlines from the end.
75	func (l *LineIndex) SpanRange(span token.Span) protocol.Range {
76	return protocol.Range{
77	Start: l.Position(span.Start.Offset),
78	End: l.Position(l.clampEnd(span.End.Offset)),
79	}
80	}
81
82	func (l *LineIndex) clampEnd(end int) int {
83	for end > 0 {
84	switch l.content[end-1] {
85	case ' ', '\t', '\r', '\n':
86	end--
87	default:
88	return end
89	}
90	}
91	return end
92	}