( filePath: string, line: number, character: number, )
| 19 | * @returns The symbol at that position, or null if extraction fails |
| 20 | */ |
| 21 | export 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) { |
no test coverage detected