Function truncate_cell 

pub fn truncate_cell(text: &str, max_width: usize, marker: &str) -> String

Truncate text to maximum visual width with ANSI code preservation

Truncates text to fit within max_width visual characters, appending marker if truncation occurs. Preserves ANSI color codes in the output.

For multiline text (containing \n), each line is truncated independently.

Arguments

• text - Input text (may contain ANSI codes and newlines)
• max_width - Maximum visual width per line (ANSI codes don’t count)
• marker - String to append when truncated (default: “…”)

Returns

Truncated string with preserved ANSI codes and marker appended. If text fits within max_width, returns original text unchanged. For multiline text, each line is truncated independently.

Examples

use tree_fmt::truncate_cell;

// Basic truncation
let result = truncate_cell( "Very long text here", 10, "..." );
assert_eq!( result, "Very lo..." );

// Multiline truncation (per-line)
let result = truncate_cell( "Long line 1\nLong line 2", 8, "..." );
assert!( result.contains( "..." ) );  // Both lines truncated

// ANSI codes preserved
let colored = "\x1b[31mRed text\x1b[0m";
let result = truncate_cell( colored, 5, "..." );
assert!( result.contains( "\x1b[31m" ) );  // Color preserved

Implementation Details

For single-line text: character-by-character iteration tracking visual position while skipping ANSI escape sequences (\x1b[...m pattern).

For multiline text: splits on \n, truncates each line independently, then joins back with \n. This ensures proper per-line truncation.