Add support for dates for increment/decrement

2 files changed, 218 insertions, 0 deletions

diff --git a/helix-core/src/date.rs b/helix-core/src/date.rs
new file mode 100644
index 00000000..1332670d
--- /dev/null
+++ b/helix-core/src/date.rs
@@ -0,0 +1,217 @@
+use chrono::{Duration, NaiveDate};
+
+use std::borrow::Cow;
+
+use ropey::RopeSlice;
+
+use crate::{
+    textobject::{textobject_word, TextObject},
+    Range, Tendril,
+};
+
+// Only support formats that aren't region specific.
+static FORMATS: &[&str] = &["%Y-%m-%d", "%Y/%m/%d"];
+
+// We don't want to parse ambiguous dates like 10/11/12 or 7/8/10.
+// They must be YYYY-mm-dd or YYYY/mm/dd.
+// So 2021-01-05 works, but 2021-1-5 doesn't.
+const DATE_LENGTH: usize = 10;
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct DateIncrementor {
+    pub date: NaiveDate,
+    pub range: Range,
+    pub format: &'static str,
+}
+
+impl DateIncrementor {
+    pub fn from_range(text: RopeSlice, range: Range) -> Option<DateIncrementor> {
+        // Don't increment if the cursor is one right of the date text.
+        if text.char(range.from()).is_whitespace() {
+            return None;
+        }
+
+        let range = textobject_word(text, range, TextObject::Inside, 1, true);
+        let text: Cow<str> = text.slice(range.from()..range.to()).into();
+
+        let first = text.chars().next()?;
+        let last = text.chars().next_back()?;
+
+        // Allow date strings in quotes.
+        let (range, text) = if first == last && (first == '"' || first == '\'') {
+            (
+                Range::new(range.from() + 1, range.to() - 1),
+                Cow::from(&text[1..text.len() - 1]),
+            )
+        } else {
+            (range, text)
+        };
+
+        if text.len() != DATE_LENGTH {
+            return None;
+        }
+
+        FORMATS.iter().find_map(|format| {
+            NaiveDate::parse_from_str(&text, format)
+                .ok()
+                .map(|date| DateIncrementor {
+                    date,
+                    range,
+                    format,
+                })
+        })
+    }
+
+    pub fn incremented_text(&self, amount: i64) -> Tendril {
+        let incremented_date = self.date + Duration::days(amount);
+        incremented_date.format(self.format).to_string().into()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::Rope;
+
+    #[test]
+    fn test_date_dashes() {
+        let rope = Rope::from_str("2021-11-15");
+        let range = Range::point(0);
+        assert_eq!(
+            DateIncrementor::from_range(rope.slice(..), range),
+            Some(DateIncrementor {
+                date: NaiveDate::from_ymd(2021, 11, 15),
+                range: Range::new(0, 10),
+                format: "%Y-%m-%d",
+            })
+        );
+    }
+
+    #[test]
+    fn test_date_slashes() {
+        let rope = Rope::from_str("2021/11/15");
+        let range = Range::point(0);
+        assert_eq!(
+            DateIncrementor::from_range(rope.slice(..), range),
+            Some(DateIncrementor {
+                date: NaiveDate::from_ymd(2021, 11, 15),
+                range: Range::new(0, 10),
+                format: "%Y/%m/%d",
+            })
+        );
+    }
+
+    #[test]
+    fn test_date_surrounded_by_spaces() {
+        let rope = Rope::from_str("   2021-11-15  ");
+        let range = Range::point(10);
+        assert_eq!(
+            DateIncrementor::from_range(rope.slice(..), range),
+            Some(DateIncrementor {
+                date: NaiveDate::from_ymd(2021, 11, 15),
+                range: Range::new(3, 13),
+                format: "%Y-%m-%d",
+            })
+        );
+    }
+
+    #[test]
+    fn test_date_in_single_quotes() {
+        let rope = Rope::from_str("date = '2021-11-15'");
+        let range = Range::point(10);
+        assert_eq!(
+            DateIncrementor::from_range(rope.slice(..), range),
+            Some(DateIncrementor {
+                date: NaiveDate::from_ymd(2021, 11, 15),
+                range: Range::new(8, 18),
+                format: "%Y-%m-%d",
+            })
+        );
+    }
+
+    #[test]
+    fn test_date_in_double_quotes() {
+        let rope = Rope::from_str("date = \"2021-11-15\"");
+        let range = Range::point(10);
+        assert_eq!(
+            DateIncrementor::from_range(rope.slice(..), range),
+            Some(DateIncrementor {
+                date: NaiveDate::from_ymd(2021, 11, 15),
+                range: Range::new(8, 18),
+                format: "%Y-%m-%d",
+            })
+        );
+    }
+
+    #[test]
+    fn test_date_cursor_one_right_of_date() {
+        let rope = Rope::from_str("2021-11-15 ");
+        let range = Range::point(10);
+        assert_eq!(DateIncrementor::from_range(rope.slice(..), range), None);
+    }
+
+    #[test]
+    fn test_date_cursor_one_left_of_number() {
+        let rope = Rope::from_str(" 2021-11-15");
+        let range = Range::point(0);
+        assert_eq!(DateIncrementor::from_range(rope.slice(..), range), None);
+    }
+
+    #[test]
+    fn test_invalid_dates() {
+        let tests = [
+            "0000-00-00",
+            "1980-2-21",
+            "1980-12-1",
+            "12345",
+            "2020-02-30",
+            "1999-12-32",
+            "19-12-32",
+            "1-2-3",
+            "0000/00/00",
+            "1980/2/21",
+            "1980/12/1",
+            "12345",
+            "2020/02/30",
+            "1999/12/32",
+            "19/12/32",
+            "1/2/3",
+        ];
+
+        for invalid in tests {
+            let rope = Rope::from_str(invalid);
+            let range = Range::point(0);
+
+            assert_eq!(DateIncrementor::from_range(rope.slice(..), range), None);
+        }
+    }
+
+    #[test]
+    fn test_increment_dates() {
+        let tests = [
+            ("1980-12-21", 1, "1980-12-22"),
+            ("1980-12-21", -1, "1980-12-20"),
+            ("1980-12-21", 100, "1981-03-31"),
+            ("1980-12-21", -100, "1980-09-12"),
+            ("1980-12-21", 1000, "1983-09-17"),
+            ("1980-12-21", -1000, "1978-03-27"),
+            ("1980/12/21", 1, "1980/12/22"),
+            ("1980/12/21", -1, "1980/12/20"),
+            ("1980/12/21", 100, "1981/03/31"),
+            ("1980/12/21", -100, "1980/09/12"),
+            ("1980/12/21", 1000, "1983/09/17"),
+            ("1980/12/21", -1000, "1978/03/27"),
+        ];
+
+        for (original, amount, expected) in tests {
+            let rope = Rope::from_str(original);
+            let range = Range::point(0);
+            assert_eq!(
+                DateIncrementor::from_range(rope.slice(..), range)
+                    .unwrap()
+                    .incremented_text(amount),
+                expected.into()
+            );
+        }
+    }
+}
diff --git a/helix-core/src/lib.rs b/helix-core/src/lib.rs
index 8ef41ef3..b16a716f 100644
--- a/helix-core/src/lib.rs
+++ b/helix-core/src/lib.rs
@@ -1,6 +1,7 @@
 pub mod auto_pairs;
 pub mod chars;
 pub mod comment;
+pub mod date;
 pub mod diagnostic;
 pub mod diff;
 pub mod graphemes;