Add Python bindings

reconcile-python/src/lib.rs

@@ -0,0 +1,235 @@
+use pyo3::prelude::*;
+use pyo3::types::{PyDict, PyList};
+use reconcile_text::{
+    BuiltinTokenizer, CursorPosition, EditedText, NumberOrText, TextWithCursors,
+};
+
+fn parse_tokenizer(tokenizer: &str) -> PyResult<BuiltinTokenizer> {
+    match tokenizer {
+        "Character" => Ok(BuiltinTokenizer::Character),
+        "Line" => Ok(BuiltinTokenizer::Line),
+        "Markdown" => Ok(BuiltinTokenizer::Markdown),
+        "Word" => Ok(BuiltinTokenizer::Word),
+        _ => Err(pyo3::exceptions::PyValueError::new_err(format!(
+            "Unknown tokenizer '{tokenizer}', expected Character, Line, Markdown, or Word"
+        ))),
+    }
+}
+
+fn extract_text_with_cursors(input: &Bound<'_, PyAny>) -> PyResult<TextWithCursors> {
+    if let Ok(text) = input.extract::<String>() {
+        return Ok(TextWithCursors::from(text));
+    }
+
+    let dict = input.downcast::<PyDict>()?;
+
+    let text: String = dict
+        .get_item("text")?
+        .ok_or_else(|| pyo3::exceptions::PyKeyError::new_err("text"))?
+        .extract()?;
+
+    let cursors = match dict.get_item("cursors")? {
+        Some(obj) if !obj.is_none() => {
+            let list = obj.downcast::<PyList>()?;
+            let mut cursors = Vec::with_capacity(list.len());
+            for item in list {
+                let cursor_dict = item.downcast::<PyDict>()?;
+                let id: usize = cursor_dict
+                    .get_item("id")?
+                    .ok_or_else(|| pyo3::exceptions::PyKeyError::new_err("id"))?
+                    .extract()?;
+                let position: usize = cursor_dict
+                    .get_item("position")?
+                    .ok_or_else(|| pyo3::exceptions::PyKeyError::new_err("position"))?
+                    .extract()?;
+                cursors.push(CursorPosition::new(id, position));
+            }
+            cursors
+        }
+        _ => Vec::new(),
+    };
+
+    Ok(TextWithCursors::new(text, cursors))
+}
+
+fn text_with_cursors_to_dict<'py>(
+    py: Python<'py>,
+    twc: &TextWithCursors,
+) -> PyResult<Bound<'py, PyDict>> {
+    let dict = PyDict::new(py);
+    dict.set_item("text", twc.text())?;
+
+    let cursors = PyList::new(
+        py,
+        twc.cursors().iter().map(|c| {
+            let d = PyDict::new(py);
+            d.set_item("id", c.id()).unwrap();
+            d.set_item("position", c.char_index()).unwrap();
+            d
+        }),
+    )?;
+    dict.set_item("cursors", cursors)?;
+
+    Ok(dict)
+}
+
+/// Merge three versions of text using conflict-free resolution.
+///
+/// Takes a parent text and two concurrent edits (left and right), returning
+/// the merged result with automatically repositioned cursors.
+///
+/// Args:
+///     parent: The original text that both sides diverged from.
+///     left: The left edit, either a string or a dict with "text" and "cursors" keys.
+///     right: The right edit, either a string or a dict with "text" and "cursors" keys.
+///     tokenizer: Tokenization strategy - "Word" (default), "Character", "Line", or "Markdown".
+///
+/// Returns:
+///     A dict with "text" (merged string) and "cursors" (list of repositioned cursors).
+#[pyfunction]
+#[pyo3(signature = (parent, left, right, tokenizer = "Word"))]
+fn reconcile<'py>(
+    py: Python<'py>,
+    parent: &str,
+    left: &Bound<'py, PyAny>,
+    right: &Bound<'py, PyAny>,
+    tokenizer: &str,
+) -> PyResult<Bound<'py, PyDict>> {
+    let tokenizer = parse_tokenizer(tokenizer)?;
+    let left = extract_text_with_cursors(left)?;
+    let right = extract_text_with_cursors(right)?;
+
+    let result = reconcile_text::reconcile(parent, &left, &right, &*tokenizer).apply();
+    text_with_cursors_to_dict(py, &result)
+}
+
+/// Merge three versions of text and return provenance history.
+///
+/// Like `reconcile`, but also returns which source each text span came from.
+///
+/// Args:
+///     parent: The original text that both sides diverged from.
+///     left: The left edit, either a string or a dict with "text" and "cursors" keys.
+///     right: The right edit, either a string or a dict with "text" and "cursors" keys.
+///     tokenizer: Tokenization strategy - "Word" (default), "Character", "Line", or "Markdown".
+///
+/// Returns:
+///     A dict with "text", "cursors", and "history" (list of dicts with "text" and "history" keys).
+#[pyfunction]
+#[pyo3(signature = (parent, left, right, tokenizer = "Word"))]
+fn reconcile_with_history<'py>(
+    py: Python<'py>,
+    parent: &str,
+    left: &Bound<'py, PyAny>,
+    right: &Bound<'py, PyAny>,
+    tokenizer: &str,
+) -> PyResult<Bound<'py, PyDict>> {
+    let tokenizer = parse_tokenizer(tokenizer)?;
+    let left = extract_text_with_cursors(left)?;
+    let right = extract_text_with_cursors(right)?;
+
+    let reconciled = reconcile_text::reconcile(parent, &left, &right, &*tokenizer);
+    let (text_with_cursors, history_spans) = reconciled.apply_with_all();
+
+    let dict = text_with_cursors_to_dict(py, &text_with_cursors)?;
+
+    let history = PyList::new(
+        py,
+        history_spans.iter().map(|span| {
+            let d = PyDict::new(py);
+            d.set_item("text", span.text()).unwrap();
+            d.set_item("history", format!("{:?}", span.history()))
+                .unwrap();
+            d
+        }),
+    )?;
+    dict.set_item("history", history)?;
+
+    Ok(dict)
+}
+
+/// Generate a compact diff between two texts.
+///
+/// Returns a list of retain counts (positive ints), delete counts (negative ints),
+/// and inserted strings.
+///
+/// Args:
+///     parent: The original text.
+///     changed: The modified text, either a string or a dict with "text" and "cursors" keys.
+///     tokenizer: Tokenization strategy - "Word" (default), "Character", "Line", or "Markdown".
+///
+/// Returns:
+///     A list of ints and strings representing the diff.
+///
+/// Raises:
+///     ValueError: If the diff computation overflows.
+#[pyfunction]
+#[pyo3(signature = (parent, changed, tokenizer = "Word"))]
+fn diff<'py>(
+    py: Python<'py>,
+    parent: &str,
+    changed: &Bound<'py, PyAny>,
+    tokenizer: &str,
+) -> PyResult<Bound<'py, PyList>> {
+    let tokenizer = parse_tokenizer(tokenizer)?;
+    let changed = extract_text_with_cursors(changed)?;
+
+    let edited = EditedText::from_strings_with_tokenizer(parent, &changed, &*tokenizer);
+    let diff_result = edited
+        .to_diff()
+        .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))?;
+
+    let list = PyList::empty(py);
+    for item in diff_result {
+        match item {
+            NumberOrText::Number(n) => list.append(n)?,
+            NumberOrText::Text(s) => list.append(s)?,
+        }
+    }
+
+    Ok(list)
+}
+
+/// Apply a compact diff to a parent text to reconstruct the changed version.
+///
+/// Args:
+///     parent: The original text.
+///     diff: A list of ints and strings (as produced by `diff`).
+///     tokenizer: Tokenization strategy - "Word" (default), "Character", "Line", or "Markdown".
+///
+/// Returns:
+///     The reconstructed text.
+///
+/// Raises:
+///     ValueError: If the diff format is invalid.
+#[pyfunction]
+#[pyo3(signature = (parent, diff, tokenizer = "Word"))]
+fn undiff(parent: &str, diff: &Bound<'_, PyList>, tokenizer: &str) -> PyResult<String> {
+    let tokenizer = parse_tokenizer(tokenizer)?;
+
+    let mut parsed: Vec<NumberOrText> = Vec::with_capacity(diff.len());
+    for item in diff {
+        if let Ok(n) = item.extract::<i64>() {
+            parsed.push(NumberOrText::Number(n));
+        } else if let Ok(s) = item.extract::<String>() {
+            parsed.push(NumberOrText::Text(s));
+        } else {
+            return Err(pyo3::exceptions::PyTypeError::new_err(
+                "Diff items must be int or str",
+            ));
+        }
+    }
+
+    EditedText::from_diff(parent, parsed, &*tokenizer)
+        .map(|edited| edited.apply().text())
+        .map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))
+}
+
+#[pymodule]
+fn _native(m: &Bound<'_, PyModule>) -> PyResult<()> {
+    m.add_function(wrap_pyfunction!(reconcile, m)?)?;
+    m.add_function(wrap_pyfunction!(reconcile_with_history, m)?)?;
+    m.add_function(wrap_pyfunction!(diff, m)?)?;
+    m.add_function(wrap_pyfunction!(undiff, m)?)?;
+    Ok(())
+}