Add TZ="timezone" support

Author: bezmuth

src/items/builder.rs

@@ -18,6 +18,7 @@ pub struct DateTimeBuilder {
     time: Option<time::Time>,
     weekday: Option<weekday::Weekday>,
     timezone: Option<time::Offset>,
+    conversion_timezone: Option<time::Offset>,
     relative: Vec<relative::Relative>,
 }
 
@@ -98,6 +99,15 @@ impl DateTimeBuilder {
         }
     }
 
+    pub(super) fn set_conversion_timezone(mut self, conversion_timezone: time::Offset) -> Result<Self, &'static str> {
+        if self.conversion_timezone.is_some() {
+            Err("TZ= cannot appear more than once")
+        } else {
+            self.conversion_timezone = Some(conversion_timezone);
+            Ok(self)
+        }
+    }
+
     pub(super) fn push_relative(mut self, relative: relative::Relative) -> Self {
         self.relative.push(relative);
         self
@@ -270,6 +280,12 @@ impl DateTimeBuilder {
             dt = with_timezone_restore(offset, dt)?;
         }
 
+        if let Some(mut offset) = self.conversion_timezone {
+            // Reuse with_timezone_restore with a swapped offset
+            offset.negative = !offset.negative;
+            dt = with_timezone_restore(offset, dt)?;
+        }
+
         Some(dt)
     }
 }

src/items/conversion_timezone.rs

@@ -0,0 +1,13 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use winnow::{ModalResult, Parser};
+
+use super::time;
+
+pub(crate) fn parse(input: &mut &str) -> ModalResult<time::Offset> {
+    let _ = "tz=\"".parse_next(input)?;
+    let tz = time::timezone(input);
+    let _ = "\" ".parse_next(input)?;
+    return tz
+}

src/items/mod.rs

@@ -38,6 +38,7 @@ mod time;
 mod timezone;
 mod weekday;
 mod year;
+mod conversion_timezone;
 
 // utility modules
 mod builder;
@@ -58,6 +59,7 @@ use crate::ParseDateTimeError;
 
 #[derive(PartialEq, Debug)]
 pub(crate) enum Item {
+    ConversionTimeZone(time::Offset),
     Timestamp(f64),
     Year(u32),
     DateTime(combined::DateTime),
@@ -212,6 +214,11 @@ fn parse_items(input: &mut &str) -> ModalResult<DateTimeBuilder> {
     loop {
         match parse_item.parse_next(input) {
             Ok(item) => match item {
+                Item::ConversionTimeZone(tz) => {
+                    builder = builder
+                        .set_conversion_timezone(tz)
+                        .map_err(|e| expect_error(input, e))?;
+                }
                 Item::Timestamp(ts) => {
                     builder = builder
                         .set_timestamp(ts)
@@ -265,6 +272,7 @@ fn parse_item(input: &mut &str) -> ModalResult<Item> {
     trace(
         "parse_item",
         alt((
+            conversion_timezone::parse.map(Item::ConversionTimeZone),
             combined::parse.map(Item::DateTime),
             date::parse.map(Item::Date),
             time::parse.map(Item::Time),