feat(lib): use nom parsers

Parsing should now be more reliable in general.

1 files changed, 28 insertions, 48 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 279000a..10a1c39 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,13 +9,17 @@ mod parser;
 
 use std::collections::{HashMap, HashSet};
 
+use parser::{offering, subtitle, title};
 use scraper::{CaseSensitivity, ElementRef, Html, Selector};
 use serde::{Deserialize, Serialize};
-use tracing::{debug, info};
+use tracing::{debug, info, warn};
 
 /// Slice used for splitting requirements for parsing.
 const SPLIT_SLICE: &[char] = &[';', ','];
 
+/// Alias to the nom error type.
+type NomError<'a> = nom::Err<nom::error::Error<&'a str>>;
+
 /// A VUW course, along with all relevant data.
 #[derive(Clone, Debug, Deserialize, Serialize)]
 #[non_exhaustive]
@@ -49,30 +53,24 @@ pub struct Course<'a> {
 }
 
 impl<'a> Course<'a> {
-	/// Parses the courde id.
+	/// Parses the course id.
 	///
-	/// # Panics
+	/// # Errors
 	///
-	/// Panics if string is sliced in the middle of a character.
-	pub fn parse_courseid(&mut self, elem: ElementRef<'a>) {
-		elem.children().for_each(|child| {
-			child.children().for_each(|c| {
-				if let Some(text) = c.value().as_text() {
-					// The actual text we're looking for
-					let text: &str = text.trim();
+	/// This function will return an error if nom fails to parse the course title or subtitle.
+	pub fn parse_courseid(&mut self, elem: ElementRef<'a>) -> Result<(), NomError> {
+		for child in elem.children().flat_map(|child| child.children()) {
+			if let Some(text) = child.value().as_text() {
+				self.title = title(text)?.1;
+			} else if let Some(text) = child
+				.first_child()
+				.and_then(|node| node.value().as_text().map(|text| &**text))
+			{
+				self.subtitle = subtitle(text)?.1;
+			}
+		}
 
-					self.title = text;
-				} else if let Some(text) = c
-					.first_child()
-					.and_then(|node| node.value().as_text().map(|text| &**text))
-				{
-					if let Some((indice, _char)) = text.char_indices().nth(1) {
-						// Skip over "-"
-						self.subtitle = text.get(indice..).expect("indice should be valid").trim();
-					}
-				}
-			});
-		});
+		Ok(())
 	}
 
 	/// Parses the course points, prerequisites, and restrictions from the given element.
@@ -158,30 +156,10 @@ impl<'a> Course<'a> {
 			.and_then(|el| el.first_child()?.value().as_text());
 
 		if let Some(details) = details {
-			let details_split: Vec<&str> = details.split(" \u{2022} ").take(2).collect();
-
-			info!("{:#?}", &details_split);
-
-			let offering = CourseOffering::new(
-				details_split
-					.last()
-					.expect("course reference number should exist")
-					.get(4..)
-					.expect("course reference number digits should start at this indice")
-					.split_whitespace()
-					.next()
-					.expect("course reference number should exist")
-					.parse::<u16>()
-					.expect("course reference number should be parseable"),
-				Trimester::try_from(
-					*details_split
-						.first()
-						.expect("trimester element should exist"),
-				)
-				.expect("should be parseable into a trimester"),
-			);
+			info!("{:#?}", &details);
 
-			self.timetable.push(offering);
+			self.timetable
+				.push(offering(details).expect("cannot parse course offering").1);
 		}
 	}
 }
@@ -256,7 +234,7 @@ pub enum Trimester {
 }
 
 impl TryFrom<&str> for Trimester {
-	type Error = String;
+	type Error = &'static str;
 
 	fn try_from(value: &str) -> Result<Self, Self::Error> {
 		match value {
@@ -269,7 +247,7 @@ impl TryFrom<&str> for Trimester {
 			"2+3/3" => Ok(Self::TwoThree),
 			"3+1/3" => Ok(Self::ThreeOne),
 			"1+2+3/3" | "2+3+1/3" | "full year" => Ok(Self::FullYear),
-			_ => Err(String::from("Invalid trimester.")),
+			_ => Err("Invalid trimester."),
 		}
 	}
 }
@@ -300,7 +278,9 @@ pub fn parse_document(document: &Html) -> HashMap<&str, Course<'_>> {
 			working_course = Course::default();
 			working_course.subject_areas.insert(subject_area);
 
-			working_course.parse_courseid(elem);
+			working_course
+				.parse_courseid(elem)
+				.expect("could not parse courseid");
 		} else if elem_value.has_class("notoffered", CaseSensitivity::CaseSensitive) {
 			working_course.offered = false;
 		} else if elem_value.has_class("subjectarea", CaseSensitivity::CaseSensitive) {