More work on parser

1 files changed, 246 insertions, 12 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 465f927..1b73bed 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,7 @@ extern crate alloc;
 #[cfg(not(feature = "std"))]
 use alloc::collections::BTreeMap as Map;
 use alloc::sync::Arc;
+use core::fmt;
 #[cfg(feature = "std")]
 use std::collections::HashMap as Map;
 
@@ -14,8 +15,8 @@ pub struct Location {
 	line: u64,
 }
 
-impl core::fmt::Display for Location {
-	fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+impl fmt::Display for Location {
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 		write!(f, "{}:{}", self.file, self.line)
 	}
 }
@@ -35,19 +36,27 @@ pub struct Configuration {
 }
 
 #[non_exhaustive]
+#[derive(Debug)]
 pub enum Error {
 	#[cfg(feature = "std")]
-	IO(std::io::Error),
+	IO(Box<str>, std::io::Error),
+	IllegalCharacter(Location, char),
+	InvalidUtf8(Location),
 	BadInt(Location, Box<str>),
 	BadUInt(Location, Box<str>),
 	BadFloat(Location, Box<str>),
 	BadBool(Location, Box<str>),
+	UnmatchedLeftBrace(Location),
+	InvalidKey(Location, Box<str>),
+	InvalidValue(Location),
+	InvalidLine(Location),
+	StrayCharsAfterQuotedString(Location),
+	UnterminatedString(Location, char),
 }
 
-#[cfg(feature = "std")]
-impl From<std::io::Error> for Error {
-	fn from(value: std::io::Error) -> Self {
-		Self::IO(value)
+impl fmt::Display for Error {
+	fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+		todo!()
 	}
 }
 
@@ -129,13 +138,238 @@ fn parse_list(_location: &Location, _string: &str) -> Vec<String> {
 	todo!()
 }
 
+/// Trait for reading configurations.
+///
+/// Ordinarily you won't need to implement this trait, since it is
+/// already implemented by any `T: `[`std::io::BufRead`] (or else `&str` and `&[u8]`,
+/// if the `std` feature is not enabled).
+pub trait Read {
+	/// Read up to the next line feed (or EOF), not including the line feed itself.
+	///
+	/// Puts the line in `line` and returns `Ok(true)`, if the end of file has been reached,
+	/// `line` is unmodified and `Ok(false)` is returned.
+	///
+	/// You don't need to check for valid UTF-8 here — that is already done in the code which uses
+	/// this trait.
+	fn read_until_lf(&mut self, line: &mut Vec<u8>) -> Result<bool>;
+}
+
+#[cfg(feature = "std")]
+impl<R: std::io::BufRead> Read for R {
+	fn read_until_lf(&mut self, line: &mut Vec<u8>) -> Result<bool> {
+		self.read_until(b'\n', line)
+			.map_err(|e| Error::IO("read error".into(), e))?;
+		if line.ends_with(b"\n") {
+			line.pop();
+			Ok(true)
+		} else {
+			Ok(!line.is_empty())
+		}
+	}
+}
+
+#[cfg(not(feature = "std"))]
+impl Read for &str {
+	fn read_until_lf(&mut self, line: &mut Vec<u8>) -> Result<bool> {
+		match self.split_once('\n') {
+			Some((pre, post)) => {
+				*self = post;
+				line.extend_from_slice(pre.as_bytes());
+				Ok(true)
+			}
+			None => {
+				if self.is_empty() {
+					return Ok(false);
+				}
+				line.extend_from_slice(self.as_bytes());
+				*self = "";
+				Ok(true)
+			}
+		}
+	}
+}
+
+#[cfg(not(feature = "std"))]
+impl Read for &[u8] {
+	fn read_until_lf(&mut self, line: &mut Vec<u8>) -> Result<bool> {
+		match self.iter().position(|&c| c == b'\n') {
+			Some(i) => {
+				line.extend_from_slice(&self[..i]);
+				*self = &self[i + 1..];
+				Ok(true)
+			}
+			None => {
+				if self.is_empty() {
+					return Ok(false);
+				}
+				line.extend_from_slice(self);
+				*self = b"";
+				Ok(true)
+			}
+		}
+	}
+}
+
+fn check_valid_key(location: &Location, s: &str) -> Result<()> {
+	if s.bytes().all(|c| {
+		c >= 0x80 || c.is_ascii_alphanumeric() || matches!(c, b'.' | b'_' | b'/' | b'*' | b'-')
+	}) {
+		Ok(())
+	} else {
+		Err(Error::InvalidKey(location.clone(), s.into()))
+	}
+}
+
+/// Returns (unquoted value, new line number)
+fn read_quoted_value(
+	quoted: &str,
+	reader: &mut dyn Read,
+	start_location: &Location,
+) -> Result<(String, u64)> {
+	let delimiter: char = quoted.chars().next().unwrap();
+	let mut unquoted = String::new();
+	let mut line_number = start_location.line;
+	let location = |line_number: u64| Location {
+		file: start_location.file.clone(),
+		line: line_number,
+	};
+	let mut line_buf = vec![];
+	let mut first = true;
+	loop {
+		let line = if first {
+			first = false;
+			quoted
+		} else {
+			line_buf.truncate(0);
+			if !reader.read_until_lf(&mut line_buf)? {
+				break;
+			}
+			line_number += 1;
+			line_buf.pop_if(|c| *c == b'\r');
+			str::from_utf8(&line_buf).map_err(|_| Error::InvalidUtf8(location(line_number)))?
+		};
+		let mut chars = line.chars();
+		while let Some(c) = chars.next() {
+			if c == delimiter {
+				if !chars.all(|c| c == ' ' || c == '\t') {
+					return Err(Error::StrayCharsAfterQuotedString(location(line_number)));
+				}
+				return Ok((unquoted, line_number));
+			} else if c == '\\' {
+				todo!() // parse escape sequence
+			} else if c == '\0' {
+				return Err(Error::InvalidValue(location(line_number)));
+			} else {
+				unquoted.push(c);
+			}
+		}
+	}
+	Err(Error::UnterminatedString(start_location.clone(), delimiter))
+}
+
 impl Configuration {
-	#[cfg(feature = "std")]
-	pub fn load<R: std::io::BufRead>(_reader: R) -> Result<Configuration> {
-		todo!()
+	fn load_dyn(filename: &str, reader: &mut dyn Read) -> Result<Self> {
+		let mut config = Configuration::default();
+		let mut line = vec![];
+		let mut line_number = 0;
+		let mut current_section = &mut config;
+		let filename: Arc<str> = filename.into();
+		loop {
+			line.truncate(0);
+			if !reader.read_until_lf(&mut line)? {
+				break;
+			}
+			line_number += 1;
+			let location = Location {
+				file: filename.clone(),
+				line: line_number,
+			};
+			line.pop_if(|c| *c == b'\r');
+			for c in &line {
+				if (0..0x1f).contains(c) && *c != b'\t' {
+					return Err(Error::IllegalCharacter(location, char::from(*c)));
+				}
+			}
+			let mut line =
+				str::from_utf8(&line).map_err(|_| Error::InvalidUtf8(location.clone()))?;
+			line = line.trim_start_matches(['\t', ' ']);
+			if line.is_empty() || line.starts_with('#') {
+				// comment/blank line
+				continue;
+			}
+			if line.starts_with('[') {
+				line = line.trim_end_matches(['\t', ' ']);
+				if !line.ends_with(']') {
+					return Err(Error::UnmatchedLeftBrace(location));
+				}
+				let new_section = line[1..line.len() - 1].into();
+				current_section = &mut config;
+				check_valid_key(&location, new_section)?;
+				if !new_section.is_empty() {
+					for component in new_section.split('.') {
+						current_section = Arc::get_mut(&mut current_section.children)
+							.unwrap()
+							.entry(component.into())
+							.or_default();
+					}
+				}
+			} else {
+				let (mut relative_key, mut value) = line
+					.split_once('=')
+					.ok_or_else(|| Error::InvalidLine(location.clone()))?;
+				check_valid_key(&location, relative_key)?;
+				relative_key = relative_key.trim_end_matches(['\t', ' ']);
+				value = value.trim_start_matches(['\t', ' ']);
+
+				fn insert(
+					mut section: &mut Configuration,
+					location: Location,
+					mut key: &str,
+					value: &str,
+				) {
+					if let Some(last_dot) = key.rfind('.') {
+						for component in key[..last_dot].split('.') {
+							section = Arc::get_mut(&mut section.children)
+								.unwrap()
+								.entry(component.into())
+								.or_default()
+						}
+						key = &key[last_dot + 1..];
+					}
+					Arc::get_mut(&mut section.values).unwrap().insert(
+						key.into(),
+						Value {
+							value: value.into(),
+							defined_at: location,
+						},
+					);
+				}
+				if value.starts_with(['`', '"', '\'']) {
+					let (value, new_line_number) = read_quoted_value(value, reader, &location)?;
+					insert(current_section, location, relative_key, &value);
+					line_number = new_line_number;
+				} else {
+					value = value.trim_end_matches(['\t', ' ']);
+					if value.contains('\0') {
+						return Err(Error::InvalidValue(location));
+					}
+					insert(current_section, location, relative_key, value);
+				}
+			}
+		}
+		Ok(config)
 	}
-	pub fn load_str(_s: &str) -> Result<Configuration> {
-		todo!()
+	pub fn load<R: Read>(filename: &str, mut reader: R) -> Result<Self> {
+		// avoid big code size by using dyn reference.
+		// the impact on performance is not really important.
+		Configuration::load_dyn(filename, &mut reader)
+	}
+	#[cfg(feature = "std")]
+	pub fn load_path<P: AsRef<std::path::Path>>(path: P) -> Result<Self> {
+		let p = path.as_ref();
+		let filename = p.to_string_lossy();
+		let file = std::fs::File::open(p).map_err(|e| Error::IO(filename.clone().into(), e))?;
+		Configuration::load(&filename, std::io::BufReader::new(file))
 	}
 	pub fn section(&self, key: &str) -> Configuration {
 		let mut node = self;