feature4 implemented and working properly well
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Priec
217
canvas/src/validation/formatting.rs
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217
canvas/src/validation/formatting.rs
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/* canvas/src/validation/formatting.rs
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Add new formatting module with CustomFormatter, PositionMapper, DefaultPositionMapper, and FormattingResult
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*/
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use std::sync::Arc;
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/// Bidirectional mapping between raw input positions and formatted display positions.
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///
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/// The library uses this to keep cursor/selection behavior intuitive when the UI
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/// shows a formatted transformation (e.g., "01001" -> "010 01") while the editor
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/// still stores raw text.
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pub trait PositionMapper: Send + Sync {
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/// Map a raw cursor position to a formatted cursor position.
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///
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/// raw_pos is an index into the raw text (0..=raw.len() in char positions).
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/// Implementations should return a position within 0..=formatted.len() (in char positions).
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fn raw_to_formatted(&self, raw: &str, formatted: &str, raw_pos: usize) -> usize;
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/// Map a formatted cursor position to a raw cursor position.
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///
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/// formatted_pos is an index into the formatted text (0..=formatted.len()).
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/// Implementations should return a position within 0..=raw.len() (in char positions).
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fn formatted_to_raw(&self, raw: &str, formatted: &str, formatted_pos: usize) -> usize;
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}
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/// A reasonable default mapper that works for "insert separators" style formatting,
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/// such as grouping digits or adding dashes/spaces.
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///
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/// Heuristic:
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/// - Treat letters and digits (is_alphanumeric) in the formatted string as user-entered characters
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/// corresponding to raw characters, in order.
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/// - Treat any non-alphanumeric characters as purely visual separators.
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/// - Raw positions are mapped by counting alphanumeric characters in the formatted string.
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/// - If the formatted contains fewer alphanumeric characters than the raw (shouldn't happen
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/// for plain grouping), we cap at the end of the formatted string.
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#[derive(Clone, Default)]
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pub struct DefaultPositionMapper;
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impl PositionMapper for DefaultPositionMapper {
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fn raw_to_formatted(&self, raw: &str, formatted: &str, raw_pos: usize) -> usize {
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// Convert to char indices for correctness in presence of UTF-8
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let raw_len = raw.chars().count();
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let clamped_raw_pos = raw_pos.min(raw_len);
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// Count alphanumerics in formatted, find the index where we've seen `clamped_raw_pos` of them.
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let mut seen_user_chars = 0usize;
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for (idx, ch) in formatted.char_indices() {
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if ch.is_alphanumeric() {
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if seen_user_chars == clamped_raw_pos {
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// Cursor is positioned before this user character in the formatted view
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return idx;
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}
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seen_user_chars += 1;
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}
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}
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// If we consumed all alphanumeric chars and still haven't reached clamped_raw_pos,
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// place cursor at the end of the formatted string.
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formatted.len()
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}
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fn formatted_to_raw(&self, raw: &str, formatted: &str, formatted_pos: usize) -> usize {
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let clamped_fmt_pos = formatted_pos.min(formatted.len());
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// Count alphanumerics in formatted up to formatted_pos.
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let mut seen_user_chars = 0usize;
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for (idx, ch) in formatted.char_indices() {
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if idx >= clamped_fmt_pos {
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break;
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}
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if ch.is_alphanumeric() {
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seen_user_chars += 1;
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}
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}
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// Map to raw position by clamping to raw char count
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let raw_len = raw.chars().count();
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seen_user_chars.min(raw_len)
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}
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}
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/// Result of invoking a custom formatter on the raw input.
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///
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/// Success variants carry the formatted string and a position mapper to translate
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/// between raw and formatted cursor positions. If you don't provide a custom mapper,
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/// the library will fall back to DefaultPositionMapper.
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pub enum FormattingResult {
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/// Successfully produced a formatted display value and a position mapper.
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Success {
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formatted: String,
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/// Mapper to convert cursor positions between raw and formatted representations.
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mapper: Arc<dyn PositionMapper>,
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},
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/// Successfully produced a formatted value, but with a non-fatal warning message
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/// that can be shown in the UI (e.g., "incomplete value").
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Warning {
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formatted: String,
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message: String,
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mapper: Arc<dyn PositionMapper>,
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},
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/// Failed to produce a formatted display. The library will typically fall back to raw.
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Error {
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message: String,
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},
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}
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impl FormattingResult {
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/// Convenience to create a success result using the default mapper.
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pub fn success(formatted: impl Into<String>) -> Self {
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FormattingResult::Success {
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formatted: formatted.into(),
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mapper: Arc::new(DefaultPositionMapper::default()),
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}
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}
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/// Convenience to create a warning result using the default mapper.
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pub fn warning(formatted: impl Into<String>, message: impl Into<String>) -> Self {
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FormattingResult::Warning {
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formatted: formatted.into(),
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message: message.into(),
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mapper: Arc::new(DefaultPositionMapper::default()),
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}
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}
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/// Convenience to create a success result with a custom mapper.
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pub fn success_with_mapper(
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formatted: impl Into<String>,
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mapper: Arc<dyn PositionMapper>,
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) -> Self {
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FormattingResult::Success {
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formatted: formatted.into(),
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mapper,
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}
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}
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/// Convenience to create a warning result with a custom mapper.
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pub fn warning_with_mapper(
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formatted: impl Into<String>,
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message: impl Into<String>,
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mapper: Arc<dyn PositionMapper>,
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) -> Self {
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FormattingResult::Warning {
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formatted: formatted.into(),
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message: message.into(),
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mapper,
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}
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}
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/// Convenience to create an error result.
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pub fn error(message: impl Into<String>) -> Self {
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FormattingResult::Error {
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message: message.into(),
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}
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}
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}
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/// A user-implemented formatter that turns raw input into a formatted display string,
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/// optionally providing a custom cursor position mapper.
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///
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/// Notes:
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/// - The library will keep raw input authoritative for editing and validation.
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/// - The formatted value is only used for display.
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/// - If formatting fails, return Error; the library will show the raw value.
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/// - For common grouping (spaces/dashes), you can return Success/Warning and rely
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/// on DefaultPositionMapper, or provide your own mapper for advanced cases
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/// (reordering, compression, locale-specific rules, etc.).
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pub trait CustomFormatter: Send + Sync {
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fn format(&self, raw: &str) -> FormattingResult;
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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struct GroupEvery3;
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impl CustomFormatter for GroupEvery3 {
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fn format(&self, raw: &str) -> FormattingResult {
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let mut out = String::new();
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for (i, ch) in raw.chars().enumerate() {
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if i > 0 && i % 3 == 0 {
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out.push(' ');
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}
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out.push(ch);
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}
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FormattingResult::success(out)
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}
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}
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#[test]
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fn default_mapper_roundtrip_basic() {
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let mapper = DefaultPositionMapper::default();
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let raw = "01001";
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let formatted = "010 01";
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// raw_to_formatted monotonicity and bounds
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for rp in 0..=raw.chars().count() {
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let fp = mapper.raw_to_formatted(raw, formatted, rp);
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assert!(fp <= formatted.len());
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}
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// formatted_to_raw bounds
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for fp in 0..=formatted.len() {
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let rp = mapper.formatted_to_raw(raw, formatted, fp);
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assert!(rp <= raw.chars().count());
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}
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}
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#[test]
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fn formatter_groups_every_3() {
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let f = GroupEvery3;
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match f.format("1234567") {
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FormattingResult::Success { formatted, .. } => {
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assert_eq!(formatted, "123 456 7");
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}
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_ => panic!("expected success"),
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}
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}
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}
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