feat: add project & registry parsing /w commands

5 files changed, 762 insertions, 0 deletions

diff --git a/src/command.rs b/src/command.rs
new file mode 100644
index 0000000..c7ada95
--- /dev/null
+++ b/src/command.rs
@@ -0,0 +1,263 @@
+//! OpenGL command.
+use crate::xml::element::{Elements, FromElements};
+
+/// A command.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Command
+{
+    prototype: Prototype,
+    parameters: Vec<Parameter>,
+}
+
+impl Command
+{
+    /// Returns a new `Command`.
+    pub fn new(
+        prototype: Prototype,
+        parameters: impl IntoIterator<Item = Parameter>,
+    ) -> Self
+    {
+        Self {
+            prototype,
+            parameters: parameters.into_iter().collect(),
+        }
+    }
+
+    /// Returns the command prototype.
+    #[must_use]
+    pub fn prototype(&self) -> &Prototype
+    {
+        &self.prototype
+    }
+
+    /// Returns the command parameters.
+    #[must_use]
+    pub fn parameters(&self) -> &[Parameter]
+    {
+        &self.parameters
+    }
+}
+
+impl FromElements for Command
+{
+    type Error = Error;
+
+    fn from_elements(
+        elements: &crate::xml::element::Elements,
+    ) -> Result<Self, Self::Error>
+    {
+        let proto_element = elements
+            .get_first_tagged_element("proto")
+            .ok_or(Self::Error::MissingPrototype)?;
+
+        let prototype = Prototype::from_elements(proto_element.child_elements())?;
+
+        let parameters = elements
+            .get_all_tagged_elements_with_name("param")
+            .into_iter()
+            .map(|param_element| Parameter::from_elements(param_element.child_elements()))
+            .collect::<Result<Vec<_>, _>>()?;
+
+        Ok(Self {
+            prototype,
+            parameters,
+        })
+    }
+}
+
+/// [`Command`] error.
+#[derive(Debug, thiserror::Error)]
+pub enum Error
+{
+    /// No 'proto' element was found.
+    #[error("No 'proto' element was found")]
+    MissingPrototype,
+
+    /// Invalid prototype.
+    #[error("Invalid prototype")]
+    InvalidPrototype(#[from] PrototypeError),
+
+    /// Invalid parameter.
+    #[error("Invalid parameter")]
+    InvalidParameter(#[from] ParameterError),
+}
+
+/// A command prototype.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Prototype
+{
+    name: String,
+    return_type: String,
+}
+
+impl Prototype
+{
+    /// Returns a new `Prototype`.
+    pub fn new(name: impl Into<String>, return_type: impl Into<String>) -> Self
+    {
+        Self {
+            name: name.into(),
+            return_type: return_type.into(),
+        }
+    }
+
+    /// Returns the command prototype name.
+    #[must_use]
+    pub fn name(&self) -> &str
+    {
+        &self.name
+    }
+
+    /// Returns the command prototype return type.
+    #[must_use]
+    pub fn return_type(&self) -> &str
+    {
+        &self.return_type
+    }
+}
+
+impl FromElements for Prototype
+{
+    type Error = PrototypeError;
+
+    fn from_elements(
+        elements: &crate::xml::element::Elements,
+    ) -> Result<Self, Self::Error>
+    {
+        let name = elements
+            .get_first_tagged_element("name")
+            .ok_or(Self::Error::MissingName)?
+            .child_elements()
+            .get_first_text_element()
+            .cloned()
+            .unwrap_or_default();
+
+        let return_type = find_type(elements);
+
+        Ok(Self { name, return_type })
+    }
+}
+
+/// [`Prototype`] error.
+#[derive(Debug, thiserror::Error)]
+pub enum PrototypeError
+{
+    /// No 'name' element was found.
+    #[error("No 'name' element was found")]
+    MissingName,
+}
+
+/// A command parameter.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Parameter
+{
+    name: String,
+    ty: String,
+}
+
+impl Parameter
+{
+    /// Returns a new `Parameter`.
+    pub fn new(name: impl Into<String>, ty: impl Into<String>) -> Self
+    {
+        Self {
+            name: name.into(),
+            ty: ty.into(),
+        }
+    }
+
+    /// Returns the name of the command parameter.
+    #[must_use]
+    pub fn name(&self) -> &str
+    {
+        &self.name
+    }
+
+    /// Returns the type of the command parameter.
+    #[must_use]
+    pub fn get_type(&self) -> &str
+    {
+        &self.ty
+    }
+}
+
+impl FromElements for Parameter
+{
+    type Error = ParameterError;
+
+    fn from_elements(elements: &Elements) -> Result<Self, Self::Error>
+    {
+        let name = elements
+            .get_first_tagged_element("name")
+            .ok_or(Self::Error::MissingName)?
+            .child_elements()
+            .get_first_text_element()
+            .cloned()
+            .unwrap_or_default();
+
+        let ty = find_type(elements);
+
+        Ok(Self { name, ty })
+    }
+}
+
+/// [`Parameter`] error.
+#[derive(Debug, thiserror::Error)]
+pub enum ParameterError
+{
+    /// No 'name' element was found.
+    #[error("No 'name' element was found")]
+    MissingName,
+}
+
+fn find_type(elements: &Elements) -> String
+{
+    let text_type_parts = elements
+        .get_all_text_elements()
+        .into_iter()
+        .map(|text_type_part| text_type_part.trim())
+        .filter(|text_type_part| !text_type_part.is_empty())
+        .collect::<Vec<_>>();
+
+    let opt_ptype_text = get_ptype_text(elements);
+
+    opt_ptype_text.map_or_else(
+        || join_space_strs(text_type_parts.iter()),
+        |ptype_text| {
+            let Some(first_part) = text_type_parts.first() else {
+                return ptype_text.clone();
+            };
+
+            let before = if *first_part == "const" { "const " } else { "" };
+
+            let after_start_index = usize::from(*first_part == "const");
+
+            format!(
+                "{before}{ptype_text} {}",
+                text_type_parts
+                    .get(after_start_index..)
+                    .map(|parts| join_space_strs(parts.iter()))
+                    .unwrap_or_default()
+            )
+        },
+    )
+}
+
+fn get_ptype_text(elements: &Elements) -> Option<&String>
+{
+    let ptype_element = elements.get_first_tagged_element("ptype")?;
+
+    ptype_element.child_elements().get_first_text_element()
+}
+
+fn join_space_strs<Strings, StrItem>(strings: Strings) -> String
+where
+    Strings: Iterator<Item = StrItem>,
+    StrItem: ToString,
+{
+    strings
+        .into_iter()
+        .map(|string| string.to_string())
+        .collect::<Vec<_>>()
+        .join(" ")
+}
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..45f9fc9
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,158 @@
+//! Rust API for the [OpenGL API and Extension Registry].
+//!
+//! [OpenGL API and Extension Registry]: https://github.com/KhronosGroup/OpenGL-Registry
+#![cfg_attr(doc_cfg, feature(doc_cfg))]
+#![deny(clippy::all, clippy::pedantic, missing_docs)]
+
+use std::fs::File;
+use std::io::Read;
+
+use crate::command::{Command, Error as CommandError};
+use crate::xml::element::{Element, Elements, FromElements};
+use crate::xml::parser::{Error as ParserError, Parser};
+
+pub mod command;
+
+mod xml;
+
+#[cfg(feature = "include-xml")]
+const GL_REGISTRY_XML: &str = include_str!("../OpenGL-Registry/xml/gl.xml");
+
+const REGISTRY_TAG_NAME: &str = "registry";
+
+/// Representation of the OpenGL registry.
+pub struct Registry
+{
+    commands: Vec<Command>,
+}
+
+impl Registry
+{
+    /// Retrieves the OpenGL registry from a included XML file.
+    ///
+    /// # Errors
+    /// Returns `Err` if parsing fails in any way.
+    #[cfg(feature = "include-xml")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "include-xml")))]
+    pub fn retrieve() -> Result<Registry, RegistryError>
+    {
+        Self::retrieve_from_bytes(GL_REGISTRY_XML.as_bytes())
+    }
+
+    /// Retrieves the OpenGL registry from XML bytes.
+    ///
+    /// # Errors
+    /// Returns `Err` if parsing fails in any way.
+    pub fn retrieve_from_bytes(xml_bytes: &[u8]) -> Result<Registry, RegistryError>
+    {
+        let mut parser = Parser::new(xml_bytes);
+
+        let elements = parser.parse().map_err(ParsingError)?;
+
+        let registry_element = elements
+            .get_first_tagged_element(REGISTRY_TAG_NAME)
+            .ok_or(RegistryError::MissingRegistryElement)?;
+
+        let registry = Registry::from_elements(registry_element.child_elements())?;
+
+        Ok(registry)
+    }
+
+    /// Retrieves the OpenGL registry from a XML file.
+    ///
+    /// # Errors
+    /// Returns `Err` if:
+    /// - Parsing fails in any way.
+    /// - An I/O error occurs.
+    pub fn retrieve_from_file(xml_file: &mut File) -> Result<Registry, RegistryError>
+    {
+        let mut buf = Vec::new();
+
+        xml_file.read_to_end(&mut buf)?;
+
+        Self::retrieve_from_bytes(&buf)
+    }
+
+    /// Creates a new `Registry`.
+    ///
+    /// # Note
+    /// This will **NOT** use anything from the actual OpenGL registry. Use the
+    /// [`Registry::retrieve`] method for that.
+    pub fn new(commands: impl IntoIterator<Item = Command>) -> Self
+    {
+        Self {
+            commands: commands.into_iter().collect(),
+        }
+    }
+
+    /// Returns the available commands.
+    #[must_use]
+    pub fn commands(&self) -> &[Command]
+    {
+        &self.commands
+    }
+}
+
+impl FromElements for Registry
+{
+    type Error = RegistryError;
+
+    fn from_elements(elements: &Elements) -> Result<Self, Self::Error>
+    {
+        let commands_element = elements
+            .get_first_tagged_element("commands")
+            .ok_or(Self::Error::MissingCommandsElement)?;
+
+        let command_elements =
+            commands_element
+                .child_elements()
+                .into_iter()
+                .filter_map(|element| match element {
+                    Element::Tagged(tagged_element)
+                        if tagged_element.name() == "command" =>
+                    {
+                        Some(tagged_element)
+                    }
+                    _ => None,
+                });
+
+        let commands = command_elements
+            .into_iter()
+            .map(|command_element| {
+                Command::from_elements(command_element.child_elements())
+            })
+            .collect::<Result<Vec<_>, _>>()?;
+
+        Ok(Self { commands })
+    }
+}
+
+/// [`Registry`] error.
+#[derive(Debug, thiserror::Error)]
+pub enum RegistryError
+{
+    /// No 'registry' element was found.
+    #[error("No 'registry' element was found")]
+    MissingRegistryElement,
+
+    /// No 'commands' element was found.
+    #[error("No 'commands' element was found")]
+    MissingCommandsElement,
+
+    /// A command is invalid.
+    #[error("Invalid command")]
+    InvalidCommand(#[from] CommandError),
+
+    /// Parsing failed.
+    #[error("Parsing failed")]
+    ParsingFailed(#[from] ParsingError),
+
+    /// I/O failed.
+    #[error("I/O failed")]
+    IOFailed(#[from] std::io::Error),
+}
+
+/// Parsing error.
+#[derive(Debug, thiserror::Error)]
+#[error(transparent)]
+pub struct ParsingError(#[from] ParserError);
diff --git a/src/xml/element.rs b/src/xml/element.rs
new file mode 100644
index 0000000..f469480
--- /dev/null
+++ b/src/xml/element.rs
@@ -0,0 +1,144 @@
+#[derive(Debug, PartialEq, Eq)]
+pub struct Elements
+{
+    elements: Vec<Element>,
+}
+
+impl Elements
+{
+    pub fn get_first_tagged_element(&self, tag_name: &str) -> Option<&Tagged>
+    {
+        self.elements.iter().find_map(|element| match element {
+            Element::Tagged(tagged_element) if tagged_element.name == tag_name => {
+                Some(tagged_element)
+            }
+            _ => None,
+        })
+    }
+
+    pub fn get_all_tagged_elements_with_name(&self, tag_name: &str) -> Vec<&Tagged>
+    {
+        self.elements
+            .iter()
+            .filter_map(|element| match element {
+                Element::Tagged(tagged_element) if tagged_element.name == tag_name => {
+                    Some(tagged_element)
+                }
+                _ => None,
+            })
+            .collect()
+    }
+
+    pub fn get_first_text_element(&self) -> Option<&String>
+    {
+        self.elements.iter().find_map(|element| match element {
+            Element::Text(text) => Some(text),
+            _ => None,
+        })
+    }
+
+    pub fn get_all_text_elements(&self) -> Vec<&String>
+    {
+        self.elements
+            .iter()
+            .filter_map(|element| match element {
+                Element::Text(text) => Some(text),
+                _ => None,
+            })
+            .collect()
+    }
+
+    pub fn has_tagged_element(&self, tag_name: &str) -> bool
+    {
+        self.elements.iter().any(|element| {
+            matches!(
+                element,
+                Element::Tagged(tagged_element) if tagged_element.name == tag_name
+            )
+        })
+    }
+}
+
+impl<IntoIter: IntoIterator<Item = Element>> From<IntoIter> for Elements
+{
+    fn from(into_iter: IntoIter) -> Self
+    {
+        Self {
+            elements: into_iter.into_iter().collect(),
+        }
+    }
+}
+
+impl<'elements> IntoIterator for &'elements Elements
+{
+    type IntoIter = Iter<'elements>;
+    type Item = &'elements Element;
+
+    fn into_iter(self) -> Self::IntoIter
+    {
+        Self::IntoIter {
+            elements: self.elements.iter(),
+        }
+    }
+}
+
+pub struct Iter<'elements>
+{
+    elements: std::slice::Iter<'elements, Element>,
+}
+
+impl<'elements> Iterator for Iter<'elements>
+{
+    type Item = &'elements Element;
+
+    fn next(&mut self) -> Option<Self::Item>
+    {
+        self.elements.next()
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum Element
+{
+    Tagged(Tagged),
+    Text(String),
+    Comment(String),
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct Tagged
+{
+    name: String,
+    child_elements: Elements,
+}
+
+impl Tagged
+{
+    pub fn new<Name, ChildElements>(name: &Name, child_elements: ChildElements) -> Self
+    where
+        Name: ToString,
+        ChildElements: Into<Elements>,
+    {
+        Self {
+            name: name.to_string(),
+            child_elements: child_elements.into(),
+        }
+    }
+
+    pub fn name(&self) -> &str
+    {
+        &self.name
+    }
+
+    pub fn child_elements(&self) -> &Elements
+    {
+        &self.child_elements
+    }
+}
+
+pub trait FromElements: Sized
+{
+    type Error;
+
+    fn from_elements(elements: &Elements) -> Result<Self, Self::Error>;
+}
diff --git a/src/xml/mod.rs b/src/xml/mod.rs
new file mode 100644
index 0000000..12368c3
--- /dev/null
+++ b/src/xml/mod.rs
@@ -0,0 +1,2 @@
+pub mod element;
+pub mod parser;
diff --git a/src/xml/parser.rs b/src/xml/parser.rs
new file mode 100644
index 0000000..d152a6e
--- /dev/null
+++ b/src/xml/parser.rs
@@ -0,0 +1,195 @@
+use std::io::BufRead;
+
+use quick_xml::events::{BytesStart, BytesText, Event};
+use quick_xml::Reader;
+
+use crate::xml::element::{Element, Elements, Tagged};
+
+/// XML parser.
+pub struct Parser<Source>
+{
+    reader: Reader<Source>,
+}
+
+impl<Source: BufRead> Parser<Source>
+{
+    pub fn new(src: Source) -> Self
+    {
+        Self {
+            reader: Reader::from_reader(src),
+        }
+    }
+
+    pub fn parse(&mut self) -> Result<Elements, Error>
+    {
+        let mut buf = Vec::new();
+
+        let mut elements = Vec::new();
+
+        loop {
+            let event = self.reader.read_event_into(&mut buf)?;
+
+            let element = match self.handle_event(event)? {
+                EventHandlingResult::Element(element) => element,
+                EventHandlingResult::Event(_) => {
+                    continue;
+                }
+                EventHandlingResult::End => {
+                    break;
+                }
+            };
+
+            elements.push(element);
+        }
+
+        Ok(elements.into())
+    }
+
+    fn parse_text(text: &BytesText) -> Result<String, Error>
+    {
+        String::from_utf8(text.to_vec()).map_err(|_| Error::TextNotUTF8)
+    }
+
+    fn parse_tagged(&mut self, start: &BytesStart) -> Result<Element, Error>
+    {
+        let mut child_elements = Vec::new();
+
+        let mut buf = Vec::new();
+
+        loop {
+            let event = self.reader.read_event_into(&mut buf)?;
+
+            match event {
+                Event::End(end) if end.name() == start.name() => {
+                    break;
+                }
+                event => match self.handle_event(event)? {
+                    EventHandlingResult::Element(element) => {
+                        child_elements.push(element);
+                    }
+                    EventHandlingResult::End => {
+                        return Err(Error::UnexpectedEndOfFile);
+                    }
+                    EventHandlingResult::Event(_) => {}
+                },
+            }
+        }
+
+        Ok(Element::Tagged(Tagged::new(
+            &String::from_utf8(start.name().as_ref().to_vec())
+                .map_err(|_| Error::TagNameNotUTF8)?,
+            child_elements,
+        )))
+    }
+
+    fn handle_event<'a>(
+        &'a mut self,
+        event: Event<'a>,
+    ) -> Result<EventHandlingResult, Error>
+    {
+        match event {
+            Event::Text(text) => Ok(EventHandlingResult::Element(Element::Text(
+                Self::parse_text(&text)?,
+            ))),
+            Event::Start(start) => {
+                Ok(EventHandlingResult::Element(self.parse_tagged(&start)?))
+            }
+            Event::End(_) => Err(Error::UnexpectedTagEnd),
+            Event::Eof => Ok(EventHandlingResult::End),
+            Event::Comment(comment_text) => Ok(EventHandlingResult::Element(
+                Element::Comment(Self::parse_text(&comment_text)?),
+            )),
+            event => Ok(EventHandlingResult::Event(event)),
+        }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error
+{
+    #[error(transparent)]
+    QuickXMLFailed(#[from] quick_xml::Error),
+
+    #[error("Text is not UTF-8")]
+    TextNotUTF8,
+
+    #[error("Tag name is not UTF-8")]
+    TagNameNotUTF8,
+
+    #[error("Unexpectedly found the end of a tag")]
+    UnexpectedTagEnd,
+
+    #[error("Unexpected end of file")]
+    UnexpectedEndOfFile,
+}
+
+enum EventHandlingResult<'event>
+{
+    Element(Element),
+    Event(Event<'event>),
+    End,
+}
+
+#[cfg(test)]
+mod tests
+{
+    use pretty_assertions::assert_eq;
+
+    use super::*;
+
+    #[test]
+    fn can_parse()
+    {
+        let mut parser = Parser::new("<foo>Hello there</foo>".as_bytes());
+
+        assert_eq!(
+            parser.parse().expect("Expected Ok"),
+            Elements::from(vec![Element::Tagged(Tagged::new(
+                &"foo",
+                vec![Element::Text("Hello there".to_string())]
+            ))])
+        );
+
+        let mut parser = Parser::new("<foo><bar>123</bar> Hello</foo>".as_bytes());
+
+        assert_eq!(
+            parser.parse().expect("Expected Ok"),
+            Elements::from(vec![Element::Tagged(Tagged::new(
+                &"foo",
+                vec![
+                    Element::Tagged(Tagged::new(
+                        &"bar",
+                        Elements::from(vec![Element::Text("123".to_string())])
+                    )),
+                    Element::Text(" Hello".to_string())
+                ]
+            ))])
+        );
+
+        let mut parser = Parser::new("".as_bytes());
+
+        assert_eq!(
+            parser.parse().expect("Expected Ok"),
+            Elements::from(Vec::new())
+        );
+
+        let mut parser = Parser::new(
+            "<foo><!--XML is awful-->Hello there<bar>123</bar></foo>".as_bytes(),
+        );
+
+        assert_eq!(
+            parser.parse().expect("Expected Ok"),
+            Elements::from(vec![Element::Tagged(Tagged::new(
+                &"foo",
+                vec![
+                    Element::Comment("XML is awful".to_string()),
+                    Element::Text("Hello there".to_string()),
+                    Element::Tagged(Tagged::new(
+                        &"bar",
+                        vec![Element::Text("123".to_string())]
+                    )),
+                ]
+            ))])
+        );
+    }
+}