nonbinary.computer
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oppi.li/claude-code
source dump of claude code
oppi.li
1import { logForDebugging } from '../../utils/debug.js'
2import { truncate } from '../../utils/format.js'
3import { getFsImplementation } from '../../utils/fsOperations.js'
4import { expandPath } from '../../utils/path.js'
5
6const MAX_READ_BYTES = 64 * 1024
7
8/**
9 * Extracts the symbol/word at a specific position in a file.
10 * Used to show context in tool use messages.
11 *
12 * @param filePath - The file path (absolute or relative)
13 * @param line - 0-indexed line number
14 * @param character - 0-indexed character position on the line
15 *
16 * Note: This uses synchronous file I/O because it is called from
17 * renderToolUseMessage (a synchronous React render function). The read is
18 * wrapped in try/catch so ENOENT and other errors fall back gracefully.
19 * @returns The symbol at that position, or null if extraction fails
20 */
21export function getSymbolAtPosition(
22 filePath: string,
23 line: number,
24 character: number,
25): string | null {
26 try {
27 const fs = getFsImplementation()
28 const absolutePath = expandPath(filePath)
29
30 // Read only the first 64KB instead of the whole file. Most LSP hover/goto
31 // targets are near recent edits; 64KB covers ~1000 lines of typical code.
32 // If the target line is past this window we fall back to null (the UI
33 // already handles that by showing `position: line:char`).
34 // eslint-disable-next-line custom-rules/no-sync-fs -- called from sync React render (renderToolUseMessage)
35 const { buffer, bytesRead } = fs.readSync(absolutePath, {
36 length: MAX_READ_BYTES,
37 })
38 const content = buffer.toString('utf-8', 0, bytesRead)
39 const lines = content.split('\n')
40
41 if (line < 0 || line >= lines.length) {
42 return null
43 }
44 // If we filled the full buffer the file continues past our window,
45 // so the last split element may be truncated mid-line.
46 if (bytesRead === MAX_READ_BYTES && line === lines.length - 1) {
47 return null
48 }
49
50 const lineContent = lines[line]
51 if (!lineContent || character < 0 || character >= lineContent.length) {
52 return null
53 }
54
55 // Extract the word/symbol at the character position
56 // Pattern matches:
57 // - Standard identifiers: alphanumeric + underscore + dollar
58 // - Rust lifetimes: 'a, 'static
59 // - Rust macros: macro_name!
60 // - Operators and special symbols: +, -, *, etc.
61 // This is more inclusive to handle various programming languages
62 const symbolPattern = /[\w$'!]+|[+\-*/%&|^~<>=]+/g
63 let match: RegExpExecArray | null
64
65 while ((match = symbolPattern.exec(lineContent)) !== null) {
66 const start = match.index
67 const end = start + match[0].length
68
69 // Check if the character position falls within this match
70 if (character >= start && character < end) {
71 const symbol = match[0]
72 // Limit length to 30 characters to avoid overly long symbols
73 return truncate(symbol, 30)
74 }
75 }
76
77 return null
78 } catch (error) {
79 // Log unexpected errors for debugging (permission issues, encoding problems, etc.)
80 // Use logForDebugging since this is a display enhancement, not a critical error
81 if (error instanceof Error) {
82 logForDebugging(
83 `Symbol extraction failed for ${filePath}:${line}:${character}: ${error.message}`,
84 { level: 'warn' },
85 )
86 }
87 // Still return null for graceful fallback to position display
88 return null
89 }
90}