Merge pull request #105 from sciyoshi/rruleset-set-from-string

Add `RRuleSet::set_from_string` to support loading rules without DTSTART

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - MSRV is bumped to `v1.74.0` from `v1.64.0`
 - Make `ParseError` and `ValidationError` public
 - `EXRULE`s are now correctly added as exrules on the `RRuleSet` when parsed from a string, instead of being incorrectly added as an rrule.
+- Add a `RRuleSet::set_from_string` method to support loading rules without DTSTART. This is useful particularly when working with the Google Calendar API.
 
 ## 0.11.0 (2023-07-18)
 

rrule/src/core/rruleset.rs

@@ -2,7 +2,7 @@ use crate::core::datetime::datetime_to_ical_format;
 use crate::core::utils::collect_with_error;
 use crate::core::DateTime;
 use crate::parser::{ContentLine, Grammar};
-use crate::{RRule, RRuleError};
+use crate::{ParseError, RRule, RRuleError};
 #[cfg(feature = "serde")]
 use serde_with::{serde_as, DeserializeFromStr, SerializeDisplay};
 use std::fmt::Display;
@@ -211,34 +211,22 @@ impl RRuleSet {
     pub fn all_unchecked(self) -> Vec<DateTime> {
         collect_with_error(self.into_iter(), &self.after, &self.before, true, None).dates
     }
-}
 
-impl FromStr for RRuleSet {
-    type Err = RRuleError;
-
-    /// Creates an [`RRuleSet`] from a string if input is valid.
-    ///
-    /// # Errors
-    ///
-    /// Returns [`RRuleError`], if iCalendar string contains invalid parts.
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        let Grammar {
-            start,
-            content_lines,
-        } = Grammar::from_str(s)?;
+    fn set_from_content_lines(self, content_lines: Vec<ContentLine>) -> Result<Self, RRuleError> {
+        let dt_start = self.dt_start;
 
         content_lines.into_iter().try_fold(
-            Self::new(start.datetime),
+            self,
             |rrule_set, content_line| match content_line {
                 ContentLine::RRule(rrule) => rrule
-                    .validate(start.datetime)
+                    .validate(dt_start)
                     .map(|rrule| rrule_set.rrule(rrule)),
                 #[allow(unused_variables)]
                 ContentLine::ExRule(exrule) => {
                     #[cfg(feature = "exrule")]
                     {
                         exrule
-                            .validate(start.datetime)
+                            .validate(dt_start)
                             .map(|exrule| rrule_set.exrule(exrule))
                     }
                     #[cfg(not(feature = "exrule"))]
@@ -256,6 +244,40 @@ impl FromStr for RRuleSet {
             },
         )
     }
+
+    /// Set the [`RRuleSet`] properties from a string. If a DTSTART is found, it will be used as the start datetime.
+    pub fn set_from_string(mut self, s: &str) -> Result<Self, RRuleError> {
+        let Grammar {
+            start,
+            content_lines,
+        } = Grammar::from_str(s)?;
+
+        if let Some(dtstart) = start {
+            self.dt_start = dtstart.datetime;
+        }
+
+        self.set_from_content_lines(content_lines)
+    }
+}
+
+impl FromStr for RRuleSet {
+    type Err = RRuleError;
+
+    /// Creates an [`RRuleSet`] from a string if input is valid.
+    ///
+    /// # Errors
+    ///
+    /// Returns [`RRuleError`], if iCalendar string contains invalid parts.
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let Grammar {
+            start,
+            content_lines,
+        } = Grammar::from_str(s)?;
+
+        let start = start.ok_or(ParseError::MissingStartDate)?;
+
+        Self::new(start.datetime).set_from_content_lines(content_lines)
+    }
 }
 
 impl Display for RRuleSet {

rrule/src/parser/mod.rs

@@ -19,7 +19,7 @@ use self::content_line::{PropertyName, StartDateContentLine};
 /// Grammar represents a well-formatted rrule input.
 #[derive(Debug, PartialEq)]
 pub(crate) struct Grammar {
-    pub start: StartDateContentLine,
+    pub start: Option<StartDateContentLine>,
     pub content_lines: Vec<ContentLine>,
 }
 
@@ -36,7 +36,7 @@ impl FromStr for Grammar {
             .iter()
             .find(|parts| matches!(parts.property_name, PropertyName::DtStart))
             .map(StartDateContentLine::try_from)
-            .ok_or(ParseError::MissingStartDate)??;
+            .transpose()?;
 
         let mut content_lines = vec![];
 
@@ -90,7 +90,7 @@ mod test {
         let tests = [
 (
     "DTSTART:19970902T090000Z\nRRULE:FREQ=YEARLY;COUNT=3\n", Grammar {
-    start: StartDateContentLine { datetime: UTC.with_ymd_and_hms(1997, 9, 2,9, 0, 0).unwrap(), timezone: Some(UTC), value: "DATE-TIME" },
+    start: Some(StartDateContentLine { datetime: UTC.with_ymd_and_hms(1997, 9, 2,9, 0, 0).unwrap(), timezone: Some(UTC), value: "DATE-TIME" }),
     content_lines: vec![
         ContentLine::RRule(RRule {
             freq: Frequency::Yearly,
@@ -101,7 +101,7 @@ mod test {
 }
 ),
 ("DTSTART:20120201T093000Z\nRRULE:FREQ=WEEKLY;INTERVAL=5;UNTIL=20130130T230000Z;BYDAY=MO,FR", Grammar {
-    start: StartDateContentLine { datetime: UTC.with_ymd_and_hms(2012, 2, 1,9, 30, 0).unwrap(), timezone: Some(UTC), value: "DATE-TIME" },
+    start: Some(StartDateContentLine { datetime: UTC.with_ymd_and_hms(2012, 2, 1,9, 30, 0).unwrap(), timezone: Some(UTC), value: "DATE-TIME" }),
     content_lines: vec![
         ContentLine::RRule(RRule {
             freq: Frequency::Weekly,
@@ -113,7 +113,7 @@ mod test {
     ]
 }),
 ("DTSTART:20120201T120000Z\nRRULE:FREQ=DAILY;COUNT=5\nEXDATE;TZID=Europe/Berlin:20120202T130000,20120203T130000", Grammar {
-    start: StartDateContentLine { datetime: UTC.with_ymd_and_hms(2012, 2, 1,12, 0, 0).unwrap(), timezone: Some(UTC), value: "DATE-TIME" },
+    start: Some(StartDateContentLine { datetime: UTC.with_ymd_and_hms(2012, 2, 1,12, 0, 0).unwrap(), timezone: Some(UTC), value: "DATE-TIME" }),
     content_lines: vec![
         ContentLine::RRule(RRule {
             freq: Frequency::Daily,
@@ -127,7 +127,7 @@ mod test {
     ]
 }),
 ("DTSTART:20120201T120000Z\nRRULE:FREQ=DAILY;COUNT=5\nEXDATE;TZID=Europe/Berlin:20120202T130000,20120203T130000\nEXRULE:FREQ=WEEKLY;COUNT=10", Grammar {
-    start: StartDateContentLine { datetime: UTC.with_ymd_and_hms(2012, 2, 1,12, 0, 0).unwrap(), timezone: Some(UTC), value: "DATE-TIME" },
+    start: Some(StartDateContentLine { datetime: UTC.with_ymd_and_hms(2012, 2, 1,12, 0, 0).unwrap(), timezone: Some(UTC), value: "DATE-TIME" }),
     content_lines: vec![
         ContentLine::RRule(RRule {
             freq: Frequency::Daily,
@@ -167,15 +167,15 @@ mod test {
     }
 
     #[test]
-    fn rejects_input_without_start_date() {
+    fn allows_input_without_start_date() {
         let tests = [
             "RRULE:FREQ=WEEKLY;INTERVAL=5;UNTIL=20130130T230000Z;BYDAY=MO,FR",
             "RDATE;TZID=Europe/Berlin:20120202T130000,20120203T130000",
             "RRULE:FREQ=DAILY;COUNT=5\nEXDATE;TZID=Europe/Berlin:20120202T130000,20120203T130000",
         ];
         for input in tests {
             let res = Grammar::from_str(input);
-            assert_eq!(res, Err(ParseError::MissingStartDate));
+            assert!(res.is_ok());
         }
     }
 }