neco-textpatch

Deterministic text patch helpers for replacing byte ranges and rewriting small named blocks without a full parser.

Patch behavior

neco-textpatch works on UTF-8 strings and validates all byte ranges against the original source before rewriting. It rejects overlapping replacements, invalid UTF-8 boundaries, and ambiguous keyed entries instead of guessing how to recover.

For simple structured text, the crate also finds named brace blocks and rewrites their contents. This is useful when a caller wants to update one config-like section while keeping the rest of the source untouched.

Usage

Replace one range

use neco_textpatch::{apply_patch, TextPatch};

let patch = TextPatch::replace(6, 11, "there").expect("valid patch");
let updated = apply_patch("hello world", &patch).expect("patch should apply");

assert_eq!(updated, "hello there");

Replace one named block

use neco_textpatch::{apply_patch, replace_block};

let source = "settings {\n  mode = \"fast\"\n}\n";
let patch = replace_block(source, "settings", "\n  mode = \"safe\"\n")
    .expect("settings block should exist");
let updated = apply_patch(source, &patch).expect("patch should apply");

assert_eq!(updated, "settings {\n  mode = \"safe\"\n}\n");

API

Item	Description
`TextPatch`	One validated byte-range replacement
`TextPatch::new(start, end, replacement)`	Build a checked patch and return `Err` on invalid ranges
`TextPatch::insert(offset, replacement)`	Insert text at one byte offset
`TextPatch::delete(start, end)` / `replace(start, end, replacement)`	Convenience constructors for deletion and replacement
`TextPatchError`	Reports invalid ranges, bounds, UTF-8 boundaries, conflicts, and block lookup failures
`PatchConflict`	Describes which two patches overlapped during validation
`validate_patches(source, patches)`	Check bounds and overlap rules against the original source
`apply_patch(source, patch)` / `apply_patches(source, patches)`	Apply one or more validated patches deterministically
`find_block_range(source, block_name)`	Locate a named brace block and return its byte range
`replace_block(source, block_name, replacement)`	Build a patch that replaces one block body
`KnownEntry`	One keyed replacement entry for block merging
`merge_known_entries(source, block_name, entries)`	Replace known keyed entries and append missing ones

License

MIT