Rethink Time parser, iterating over characters

src/time/error.rs

@@ -1,8 +1,10 @@
 use std::{fmt, num::ParseIntError};
+use super::parser::Mode;
 
 #[derive(Debug)]
 pub enum Error {
     ParseInt,
+    UnexpectedChar(Mode, char),
     InvalidMonth,
     InvalidDay,
     InvalidHour,
@@ -12,6 +14,7 @@ pub enum Error {
     InvalidOffset,
     TrailingGarbage,
     Truncated,
+    MissingSeparator,
 }
 
 impl fmt::Display for Error {

src/time/parser.rs

@@ -7,8 +7,8 @@ enum Format {
     Extended,
 }
 
-#[derive(Debug, PartialEq)]
-enum Mode {
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Mode {
     Year,
     Month,
     Day,
@@ -24,9 +24,11 @@ pub struct Parser<'a> {
     text: &'a str,
     format: Format,
     mode: Mode,
+    buffer: String,
     year: Option<u32>,
     month: Option<u8>,
     day: Option<u8>,
+    sep: bool,
     hour: Option<u8>,
     minute: Option<u8>,
     second: Option<u8>,
@@ -37,11 +39,13 @@ impl<'a> Parser<'a> {
     pub fn new(text: &'a str) -> Self {
         Self {
             text,
-            format: Format::Extended,
+            format: Format::Basic,
+            buffer: String::new(),
             mode: Mode::Year,
             year: None,
             month: None,
             day: None,
+            sep: false,
             hour: None,
             minute: None,
             second: None,
@@ -49,230 +53,203 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn parse_year(&mut self) -> Result<(), Error> {
-        assert_eq!(self.mode, Mode::Year);
-        let year = self.text.get(..3).ok_or(Error::Truncated)?.parse()?;
-        self.year = Some(year);
-        if let Some(c) = self.text.chars().nth(5) {
-            match c {
-                '-' => self.format = Format::Extended,
-                _ => self.format = Format::Basic,
-            }
-        }
-        self.mode = Mode::Month;
-        Ok(())
-    }
-
-    fn parse_month(&mut self) -> Result<(), Error> {
-        assert_eq!(self.mode, Mode::Month);
-        let month = match self.format {
-            Format::Basic => self.text.get(4..6),
-            Format::Extended => self.text.get(5..7),
-        };
-        if let Some(m) = month {
-            let month = match m.parse() {
-                Ok(m) => m,
-                Err(_) => {
-                    self.mode = Mode::TimeZone;
-                    return Ok(());
+    fn number(&mut self, c: char) -> Result<(), Error> {
+        self.buffer.push(c);
+        match self.mode {
+            Mode::Year => {
+                if self.buffer.len() == 4 {
+                    let y: u32 = self.buffer.parse()?;
+                    self.buffer.clear();
+                    self.year = Some(y);
+                    self.mode = Mode::Month;
                 }
-            };
-            if month > 12 {
-                return Err(Error::InvalidMonth);
             }
-            self.month = Some(month);
-            self.mode = Mode::Day;
-        } else {
-            self.mode = Mode::TimeZone;
-        }
-        Ok(())
-    }
-
-    fn parse_day(&mut self) -> Result<(), Error> {
-        assert_eq!(self.mode, Mode::Day);
-        let day = match self.format {
-            Format::Basic => self.text.get(6..8),
-            Format::Extended => self.text.get(8..10),
-        };
-        if let Some(d) = day {
-            let day = match d.parse() {
-                Ok(d) => d,
-                Err(_) => {
-                    self.mode = Mode::TimeZone;
-                    return Ok(());
+            Mode::Month => {
+                if self.buffer.len() == 2 {
+                    let m: u8 = self.buffer.parse()?;
+                    self.buffer.clear();
+                    self.month = Some(m);
+                    self.mode = Mode::Day;
+                    self.sep = false;
                 }
-            };
-            let max = match self.month {
-                Some(1|3|5|7|10|12) => 31,
-                Some(2) => {
-                    if self.year.unwrap() % 4 == 0 {
-                        29
-                    } else {
-                        28
+            }
+            Mode::Day => {
+                if self.buffer.len() == 2 {
+                    let d: u8 = self.buffer.parse()?;
+                    self.buffer.clear();
+                    self.day = Some(d);
+                    self.mode = Mode::Hour;
+                    self.sep = false;
+                } else if self.format == Format::Extended && !self.sep {
+                    return Err(Error::MissingSeparator);
+                }
+            }
+            Mode::Hour => {
+                if self.buffer.len() == 2 {
+                    let h: u8 = self.buffer.parse()?;
+                    self.buffer.clear();
+                    self.hour = Some(h);
+                    self.mode = Mode::Minute;
+                    self.sep = false;
+                } else if self.format == Format::Extended && !self.sep {
+                    return Err(Error::MissingSeparator);
+                }
+            }
+            Mode::Minute => {
+                if self.buffer.len() == 2 {
+                    let m = self.buffer.parse()?;
+                    self.buffer.clear();
+                    self.minute = Some(m);
+                    self.mode = Mode::Second;
+                    self.sep = false;
+                } else if self.format == Format::Extended && !self.sep {
+                    return Err(Error::MissingSeparator);
+                }
+            }
+            Mode::Second => {
+                if self.buffer.len() == 2 {
+                    let s = self.buffer.parse()?;
+                    self.buffer.clear();
+                    self.second = Some(s);
+                    self.mode = Mode::TimeZone;
+                    self.sep = false;
+                } else if self.format == Format::Extended && !self.sep {
+                    return Err(Error::MissingSeparator);
+                }
+            }
+            Mode::TimeZone => match self.format {
+                Format::Basic => {
+                    if self.buffer.len() == 5 {
+                        self.mode = Mode::Finish;
                     }
                 },
-                Some(4|6|9|11) => 30,
-                _ => return Err(Error::InvalidMonth),
-            };
-            if day > max {
-                return Err(Error::InvalidDay);
-            }
-            self.day = Some(day);
-            let tidx = match self.format {
-                Format::Basic => 8,
-                Format::Extended => 10,
-            };
-            if let Some(c) = self.text.chars().nth(tidx) {
-                match c {
-                    'T' => self.mode = Mode::Hour,
-                    'Z' | '-' | '+' => self.mode = Mode::TimeZone,
-                    _ => return Err(Error::InvalidHour),
-                }
-            } else {
-                self.mode = Mode::Finish;
-            }
-        } else {
-            self.mode = Mode::TimeZone;
+                Format::Extended => {
+                    if self.buffer.len() > 3 && !self.sep {
+                        return Err(Error::MissingSeparator);
+                    } else if self.buffer.len() == 5 {
+                        self.mode = Mode::Finish;
+                    }
+                },
+            },
+            Mode::Finish => return Err(Error::TrailingGarbage),
         }
         Ok(())
     }
 
-    fn parse_hour(&mut self) -> Result<(), Error> {
-        assert_eq!(self.mode, Mode::Hour);
-        let hour = match self.format {
-            Format::Basic => self.text.get(9..11),
-            Format::Extended => self.text.get(11..13),
-        };
-        if let Some(h) = hour {
-            let hour = match h.parse() {
-                Ok(h) => h,
-                Err(_) => {
-                    self.mode = Mode::TimeZone;
-                    return Ok(());
-                }
-            };
-            if hour > 24 {
-                return Err(Error::InvalidHour);
-            }
-            self.hour = Some(hour);
-            self.mode = Mode::Minute;
-        } else {
-            self.mode = Mode::TimeZone;
-        }
-        Ok(())
-    }
-
-    fn parse_minute(&mut self) -> Result<(), Error> {
-        assert_eq!(self.mode, Mode::Minute);
-        let minute = match self.format {
-            Format::Basic => self.text.get(11..13),
-            Format::Extended => self.text.get(14..16),
-        };
-        if let Some(m) = minute {
-            let minute = match m.parse() {
-                Ok(m) => m,
-                Err(_) => {
-                    self.mode = Mode::TimeZone;
-                    return Ok(());
-                }
-            };
-            if minute > 60 {
-                return Err(Error::InvalidMinute);
-            }
-            self.minute = Some(minute);
-            self.mode = Mode::Second;
-        } else {
-            self.mode = Mode::TimeZone;
-        }
-        Ok(())
-    }
-
-    fn parse_second(&mut self) -> Result<(), Error> {
-        assert_eq!(self.mode, Mode::Second);
-        let second = match self.format {
-            Format::Basic => self.text.get(13..15),
-            Format::Extended => self.text.get(17..19),
-        };
-        if let Some(s) = second {
-            let second = match s.parse() {
-                Ok(s) => s,
-                Err(_) => {
-                    self.mode = Mode::TimeZone;
-                    return Ok(());
-                }
-            };
-            if second > 60 {
-                return Err(Error::InvalidSecond);
-            }
-            self.second = Some(second);
-        }
-        self.mode = Mode::TimeZone;
-        Ok(())
-    }
-
-    fn parse_timezone(&mut self) -> Result<(), Error> {
-        assert_eq!(self.mode, Mode::TimeZone);
-        let idx = if self.second.is_some() {
-            match self.format {
-                Format::Basic => 17,
-                Format::Extended => 21,
-            }
-        } else if self.minute.is_some() {
-            match self.format {
-                Format::Basic => 15,
-                Format::Extended => 19,
-            }
-        } else if self.hour.is_some() {
-            match self.format {
-                Format::Basic => 13,
-                Format::Extended => 16,
-            }
-        } else if self.day.is_some() {
-            match self.format {
-                Format::Basic => 9,
-                Format::Extended => 11,
-            }
-        } else if self.month.is_some() {
-            match self.format {
-                Format::Basic => 6,
-                Format::Extended => 8,
-            }
-        } else {
-            4
-        };
-        match self.text.chars().nth(idx) {
-            Some('Z') => {
-                if self.text.len() > idx + 2 {
-                    return Err(Error::TrailingGarbage);
+    fn dash(&mut self, c: char) -> Result<(), Error> {
+        match self.mode {
+            Mode::Year => return Err(Error::UnexpectedChar(Mode::Year, '-')),
+            Mode::Month => {
+                if self.month.is_some() {
+                    return Err(Error::UnexpectedChar(self.mode, '-'));
                 } else {
-                    self.tz = Some(TimeZone::UTC);
-                    return Ok(());
+                    self.format = Format::Extended;
+                    self.sep = true;
                 }
             },
-            Some('-') => todo!(),
-            Some('+') => todo!(),
-            None => self.mode = Mode::Finish,
-            _ => return Err(Error::InvalidTimezone),
+            Mode::Day => {
+                if self.day.is_some() || self.format == Format::Basic {
+                    return Err(Error::UnexpectedChar(self.mode, '-'));
+                } else {
+                    self.sep = true;
+                }
+            },
+            Mode::Hour | Mode::Minute | Mode::Second => {
+                if !self.buffer.is_empty() {
+                    return Err(Error::UnexpectedChar(self.mode, '-'));
+                } else {
+                    self.buffer.push('-');
+                    self.mode = Mode::TimeZone;
+                }
+            },
+            Mode::TimeZone => {
+                if self.buffer.is_empty() {
+                    self.buffer.push('-');
+                } else {
+                    return Err(Error::UnexpectedChar(self.mode, '-'));
+                }
+            },
+            Mode::Finish => return Err(Error::TrailingGarbage),
         }
+        Ok(())
+    }
+
+    fn colon(&mut self, c: char) -> Result<(), Error> {
+        match self.mode {
+            Mode::Year | Mode::Month | Mode::Day => return Err(Error::UnexpectedChar(self.mode, ':')),
+            Mode::Hour | Mode::Minute | Mode::Second => {
+                if !self.buffer.is_empty() || self.format == Format::Basic {
+                    return Err(Error::UnexpectedChar(self.mode, ':'));
+                } else {
+                    self.sep = true;
+                }
+            },
+            Mode::TimeZone => {
+                if !self.buffer.len() == 2 || self.format == Format::Basic {
+                    return Err(Error::UnexpectedChar(self.mode, ':'));
+                } else {
+                    self.sep = true;
+                }
+            },
+            Mode::Finish => return Err(Error::TrailingGarbage),
+        }
+        Ok(())
+    }
+
+    fn tee(&mut self, c: char) -> Result<(), Error> {
+        if self.mode != Mode::Hour || !self.buffer.is_empty() {
+            Err(Error::UnexpectedChar(self.mode, 'T'))
+        } else {
+            self.sep = true;
+            Ok(())
+        }
+    }
+
+    fn zed(&mut self, c: char) -> Result<(), Error> {
+        if self.mode == Mode::Year || !self.buffer.is_empty() {
+            return Err(Error::UnexpectedChar(self.mode, 'Z'));
+        } else {
+            self.tz = Some(TimeZone::UTC);
+            self.mode = Mode::Finish;
+        }
+        Ok(())
+    }
+
+    fn parse_tz_basic(&mut self) -> Result<(), Error> {
         todo!()
     }
 
+    fn parse_tz_extended(&mut self) -> Result<(), Error> {
+        if !self.sep {
+            Err(Error::MissingSeparator)
+        } else {
+            self.parse_tz_basic()
+        }
+    }
+
     pub fn parse(mut self) -> Result<DateTime, Error> {
-        loop {
-            match self.mode {
-                Mode::Year => self.parse_year()?,
-                Mode::Month => self.parse_month()?,
-                Mode::Day => self.parse_day()?,
-                Mode::Hour => self.parse_hour()?,
-                Mode::Minute => self.parse_minute()?,
-                Mode::Second => self.parse_second()?,
-                Mode::TimeZone => {
-                    self.parse_timezone()?;
-                    break;
-                }
-                Mode::Finish => break,
+        for c in self.text.chars() {
+            match c {
+                x if x.is_numeric() => self.number(c)?,
+                '-' => self.dash(c)?,
+                ':' => self.colon(c)?,
+                'T' => self.tee(c)?,
+                'Z' => self.zed(c)?,
+                _ => return Err(Error::UnexpectedChar(self.mode, c)),
             }
         }
+        match self.mode {
+            Mode::TimeZone | Mode::Finish => {
+                if self.tz == Some(TimeZone::UTC) && !self.buffer.is_empty() {
+                    return Err(Error::TrailingGarbage);
+                }
+                match self.format {
+                    Format::Basic => self.parse_tz_basic()?,
+                    Format::Extended => self.parse_tz_extended()?,
+                }
+            },
+            _ => return Err(Error::Truncated),
+        }
         Ok(DateTime {
             year: self.year.unwrap(),
             month: self.month,

src/time/parser.rs.bak

@@ -0,0 +1,286 @@
+//! Implements a parser for ISO-8601 format Time
+use super::{DateTime, Error, TimeZone};
+
+#[derive(Debug, PartialEq)]
+enum Format {
+    Basic,
+    Extended,
+}
+
+#[derive(Debug, PartialEq)]
+enum Mode {
+    Year,
+    Month,
+    Day,
+    Hour,
+    Minute,
+    Second,
+    TimeZone,
+    Finish,
+}
+
+#[derive(Debug)]
+pub struct Parser<'a> {
+    text: &'a str,
+    format: Format,
+    mode: Mode,
+    year: Option<u32>,
+    month: Option<u8>,
+    day: Option<u8>,
+    hour: Option<u8>,
+    minute: Option<u8>,
+    second: Option<u8>,
+    tz: Option<TimeZone>,
+}
+
+impl<'a> Parser<'a> {
+    pub fn new(text: &'a str) -> Self {
+        Self {
+            text,
+            format: Format::Extended,
+            mode: Mode::Year,
+            year: None,
+            month: None,
+            day: None,
+            hour: None,
+            minute: None,
+            second: None,
+            tz: None,
+        }
+    }
+
+    fn parse_year(&mut self) -> Result<(), Error> {
+        assert_eq!(self.mode, Mode::Year);
+        let year = self.text.get(..3).ok_or(Error::Truncated)?.parse()?;
+        self.year = Some(year);
+        if let Some(c) = self.text.chars().nth(5) {
+            match c {
+                '-' => self.format = Format::Extended,
+                _ => self.format = Format::Basic,
+            }
+        }
+        self.mode = Mode::Month;
+        Ok(())
+    }
+
+    fn parse_month(&mut self) -> Result<(), Error> {
+        assert_eq!(self.mode, Mode::Month);
+        let month = match self.format {
+            Format::Basic => self.text.get(4..6),
+            Format::Extended => self.text.get(5..7),
+        };
+        if let Some(m) = month {
+            let month = match m.parse() {
+                Ok(m) => m,
+                Err(_) => {
+                    self.mode = Mode::TimeZone;
+                    return Ok(());
+                }
+            };
+            if month > 12 {
+                return Err(Error::InvalidMonth);
+            }
+            self.month = Some(month);
+            self.mode = Mode::Day;
+        } else {
+            self.mode = Mode::TimeZone;
+        }
+        Ok(())
+    }
+
+    fn parse_day(&mut self) -> Result<(), Error> {
+        assert_eq!(self.mode, Mode::Day);
+        let day = match self.format {
+            Format::Basic => self.text.get(6..8),
+            Format::Extended => self.text.get(8..10),
+        };
+        if let Some(d) = day {
+            let day = match d.parse() {
+                Ok(d) => d,
+                Err(_) => {
+                    self.mode = Mode::TimeZone;
+                    return Ok(());
+                }
+            };
+            let max = match self.month {
+                Some(1|3|5|7|10|12) => 31,
+                Some(2) => {
+                    if self.year.unwrap() % 4 == 0 {
+                        29
+                    } else {
+                        28
+                    }
+                },
+                Some(4|6|9|11) => 30,
+                _ => return Err(Error::InvalidMonth),
+            };
+            if day > max {
+                return Err(Error::InvalidDay);
+            }
+            self.day = Some(day);
+            let tidx = match self.format {
+                Format::Basic => 8,
+                Format::Extended => 10,
+            };
+            if let Some(c) = self.text.chars().nth(tidx) {
+                match c {
+                    'T' => self.mode = Mode::Hour,
+                    'Z' | '-' | '+' => self.mode = Mode::TimeZone,
+                    _ => return Err(Error::InvalidHour),
+                }
+            } else {
+                self.mode = Mode::Finish;
+            }
+        } else {
+            self.mode = Mode::TimeZone;
+        }
+        Ok(())
+    }
+
+    fn parse_hour(&mut self) -> Result<(), Error> {
+        assert_eq!(self.mode, Mode::Hour);
+        let hour = match self.format {
+            Format::Basic => self.text.get(9..11),
+            Format::Extended => self.text.get(11..13),
+        };
+        if let Some(h) = hour {
+            let hour = match h.parse() {
+                Ok(h) => h,
+                Err(_) => {
+                    self.mode = Mode::TimeZone;
+                    return Ok(());
+                }
+            };
+            if hour > 24 {
+                return Err(Error::InvalidHour);
+            }
+            self.hour = Some(hour);
+            self.mode = Mode::Minute;
+        } else {
+            self.mode = Mode::TimeZone;
+        }
+        Ok(())
+    }
+
+    fn parse_minute(&mut self) -> Result<(), Error> {
+        assert_eq!(self.mode, Mode::Minute);
+        let minute = match self.format {
+            Format::Basic => self.text.get(11..13),
+            Format::Extended => self.text.get(14..16),
+        };
+        if let Some(m) = minute {
+            let minute = match m.parse() {
+                Ok(m) => m,
+                Err(_) => {
+                    self.mode = Mode::TimeZone;
+                    return Ok(());
+                }
+            };
+            if minute > 60 {
+                return Err(Error::InvalidMinute);
+            }
+            self.minute = Some(minute);
+            self.mode = Mode::Second;
+        } else {
+            self.mode = Mode::TimeZone;
+        }
+        Ok(())
+    }
+
+    fn parse_second(&mut self) -> Result<(), Error> {
+        assert_eq!(self.mode, Mode::Second);
+        let second = match self.format {
+            Format::Basic => self.text.get(13..15),
+            Format::Extended => self.text.get(17..19),
+        };
+        if let Some(s) = second {
+            let second = match s.parse() {
+                Ok(s) => s,
+                Err(_) => {
+                    self.mode = Mode::TimeZone;
+                    return Ok(());
+                }
+            };
+            if second > 60 {
+                return Err(Error::InvalidSecond);
+            }
+            self.second = Some(second);
+        }
+        self.mode = Mode::TimeZone;
+        Ok(())
+    }
+
+    fn parse_timezone(&mut self) -> Result<(), Error> {
+        assert_eq!(self.mode, Mode::TimeZone);
+        let idx = if self.second.is_some() {
+            match self.format {
+                Format::Basic => 17,
+                Format::Extended => 21,
+            }
+        } else if self.minute.is_some() {
+            match self.format {
+                Format::Basic => 15,
+                Format::Extended => 19,
+            }
+        } else if self.hour.is_some() {
+            match self.format {
+                Format::Basic => 13,
+                Format::Extended => 16,
+            }
+        } else if self.day.is_some() {
+            match self.format {
+                Format::Basic => 9,
+                Format::Extended => 11,
+            }
+        } else if self.month.is_some() {
+            match self.format {
+                Format::Basic => 6,
+                Format::Extended => 8,
+            }
+        } else {
+            4
+        };
+        match self.text.chars().nth(idx) {
+            Some('Z') => {
+                if self.text.len() > idx + 2 {
+                    return Err(Error::TrailingGarbage);
+                } else {
+                    self.tz = Some(TimeZone::UTC);
+                    return Ok(());
+                }
+            },
+            Some('-') => todo!(),
+            Some('+') => todo!(),
+            None => self.mode = Mode::Finish,
+            _ => return Err(Error::InvalidTimezone),
+        }
+        todo!()
+    }
+
+    pub fn parse(mut self) -> Result<DateTime, Error> {
+        loop {
+            match self.mode {
+                Mode::Year => self.parse_year()?,
+                Mode::Month => self.parse_month()?,
+                Mode::Day => self.parse_day()?,
+                Mode::Hour => self.parse_hour()?,
+                Mode::Minute => self.parse_minute()?,
+                Mode::Second => self.parse_second()?,
+                Mode::TimeZone => {
+                    self.parse_timezone()?;
+                    break;
+                }
+                Mode::Finish => break,
+            }
+        }
+        Ok(DateTime {
+            year: self.year.unwrap(),
+            month: self.month,
+            day: self.day,
+            hour: self.hour,
+            minute: self.minute,
+            second: self.second,
+            tz: self.tz,
+        })
+    }
+}