feat: add project & getting function entries

6 files changed, 812 insertions, 0 deletions

diff --git a/src/description.rs b/src/description.rs
new file mode 100644
index 0000000..ba37abc
--- /dev/null
+++ b/src/description.rs
@@ -0,0 +1,211 @@
+//! Reference entry description.
+use crate::util::enum_with_get_inner;
+use crate::xml::element::{Elements, FromElements, Tagged};
+
+/// Reference entry description.
+#[derive(Debug)]
+pub struct Description
+{
+    paragraphs: Vec<Paragraph>,
+}
+
+impl Description
+{
+    /// Returns a new `ReferenceDescription`.
+    #[must_use]
+    pub fn new() -> Self
+    {
+        Self {
+            paragraphs: Vec::new(),
+        }
+    }
+
+    /// Returns the reference description's paragraphs.
+    #[must_use]
+    pub fn paragraphs(&self) -> &[Paragraph]
+    {
+        &self.paragraphs
+    }
+}
+
+impl Default for Description
+{
+    fn default() -> Self
+    {
+        Self::new()
+    }
+}
+
+impl FromElements for Description
+{
+    type Error = Error;
+
+    fn from_elements(elements: &Elements) -> Result<Self, Self::Error>
+    {
+        let paragraphs = elements
+            .get_all_tagged_elements_with_name("para")
+            .into_iter()
+            .map(|paragraph_element| {
+                Paragraph::from_elements(paragraph_element.child_elements())
+            })
+            .collect::<Result<Vec<_>, _>>()?;
+
+        Ok(Description { paragraphs })
+    }
+}
+
+/// [`Description`] error.
+#[derive(Debug, thiserror::Error)]
+pub enum Error
+{
+    /// Invalid paragraph.
+    #[error("Invalid paragraph")]
+    InvalidParagraph(#[from] ParagraphError),
+}
+
+/// Reference entry description paragraph.
+#[derive(Debug)]
+pub struct Paragraph
+{
+    parts: Vec<ParagraphPart>,
+}
+
+impl Paragraph
+{
+    /// Returns the parts of the paragraph.
+    #[must_use]
+    pub fn parts(&self) -> &[ParagraphPart]
+    {
+        &self.parts
+    }
+}
+
+impl FromElements for Paragraph
+{
+    type Error = ParagraphError;
+
+    fn from_elements(elements: &Elements) -> Result<Self, Self::Error>
+    {
+        let parts = elements
+            .into_iter()
+            .map(|element| {
+                ParagraphPart::from_elements(&Elements::from([element.clone()]))
+            })
+            .collect::<Result<Vec<_>, _>>()?;
+
+        Ok(Self { parts })
+    }
+}
+
+/// [`Paragraph`] error.
+#[derive(Debug, thiserror::Error)]
+pub enum ParagraphError
+{
+    /// Invalid reference description part.
+    #[error("Invalid part")]
+    InvalidPart(#[from] ParagraphPartError),
+}
+
+enum_with_get_inner! {
+inner = String;
+
+/// Reference entry description paragraph part.
+#[derive(Debug)]
+pub enum ParagraphPart
+{
+    /// Text part.
+    Text(String),
+
+    /// <constant>..</constant> part.
+    Constant(String),
+
+    /// <function>..</function> part.
+    Function(String),
+
+    /// <parameter>..</parameter> part.
+    Parameter(String),
+
+    /// Reference entry citation part.
+    Entry(String),
+}
+}
+
+impl FromElements for ParagraphPart
+{
+    type Error = ParagraphPartError;
+
+    fn from_elements(elements: &Elements) -> Result<Self, Self::Error>
+    {
+        if let Some(tagged_element) = elements.get_first_tagged() {
+            return Self::from_tagged_element(tagged_element);
+        }
+
+        let text = elements
+            .get_first_text_element()
+            .ok_or(Self::Error::InputIsComment)?;
+
+        Ok(Self::Text(text.clone()))
+    }
+}
+
+impl ParagraphPart
+{
+    fn from_tagged_element(
+        tagged_element: &Tagged,
+    ) -> Result<Self, <Self as FromElements>::Error>
+    {
+        let create: fn(String) -> Self = match tagged_element.name() {
+            "constant" => Self::Constant,
+            "function" => Self::Function,
+            "parameter" => Self::Parameter,
+            "citerefentry" => Self::Entry,
+            _ => {
+                return Err(<Self as FromElements>::Error::UnknownPart(
+                    tagged_element.name().to_string(),
+                ));
+            }
+        };
+
+        if tagged_element.name() == "citerefentry" {
+            let title_element = tagged_element
+                .child_elements()
+                .get_first_tagged_with_name("refentrytitle")
+                .ok_or(<Self as FromElements>::Error::NoEntryTitleFound)?;
+
+            let title = title_element
+                .child_elements()
+                .get_first_text_element()
+                .ok_or(<Self as FromElements>::Error::NoTextInTagged)?;
+
+            return Ok(Self::Entry(title.clone()));
+        }
+
+        let text_element = tagged_element
+            .child_elements()
+            .get_first_text_element()
+            .ok_or(<Self as FromElements>::Error::NoTextInTagged)?;
+
+        Ok(create(text_element.clone()))
+    }
+}
+
+/// [`ParagraphPart`] error.
+#[derive(Debug, thiserror::Error)]
+pub enum ParagraphPartError
+{
+    /// Input element is a comment.
+    #[error("Input element is a comment")]
+    InputIsComment,
+
+    /// A input element is a unknown reference description part.
+    #[error("Input element with name '{0}' is a unknown reference description part")]
+    UnknownPart(String),
+
+    /// No text was found in tagged input element.
+    #[error("No text was found in tagged input element")]
+    NoTextInTagged,
+
+    /// No entry title found.
+    #[error("No entry title found")]
+    NoEntryTitleFound,
+}
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..8e9e1e7
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,158 @@
+//! Rust API for the [OpenGL reference page sources].
+//!
+//! [OpenGL reference page sources]: https://github.com/KhronosGroup/OpenGL-Refpages
+#![cfg_attr(doc_cfg, feature(doc_cfg))]
+#![deny(clippy::all, clippy::pedantic, missing_docs)]
+
+use std::os::unix::prelude::OsStrExt;
+
+use include_dir::{include_dir, Dir};
+
+use crate::description::{Description, Error as DescriptionError};
+use crate::xml::element::{Attribute, Elements, FromElements};
+use crate::xml::parser::{Error as ParserError, Parser};
+
+pub mod description;
+
+mod util;
+mod xml;
+
+static GL4_DIR: Dir = include_dir!("$CARGO_MANIFEST_DIR/OpenGL-Refpages/gl4");
+
+/// Reference entry.
+#[derive(Debug)]
+pub struct ReferenceEntry
+{
+    purpose: String,
+    description: Description,
+}
+
+impl ReferenceEntry
+{
+    /// Returns a function reference entry.
+    ///
+    /// # Errors
+    /// Returns `Err` if
+    /// - No reference entry file was found.
+    /// - Parsing the reference entry file data fails.
+    /// - The reference entry file data is invalid.
+    pub fn get_function(function_name: &str) -> Result<Self, ReferenceEntryError>
+    {
+        let function_file = GL4_DIR
+            .files()
+            .find_map(|file| {
+                if file.path().extension()?.as_bytes() != b"xml" {
+                    return None;
+                }
+
+                if function_name.starts_with(file.path().file_stem()?.to_str()?) {
+                    Some(file)
+                } else {
+                    None
+                }
+            })
+            .ok_or_else(|| ReferenceEntryError::NoFileFound(function_name.to_string()))?;
+
+        let function_ref_content = function_file.contents();
+
+        let mut parser = Parser::new(function_ref_content);
+
+        let root_elements = parser.parse()?;
+
+        ReferenceEntry::from_elements(&root_elements)
+    }
+
+    /// Returns the reference entry purpose.
+    #[must_use]
+    pub fn purpose(&self) -> &str
+    {
+        &self.purpose
+    }
+
+    /// Returns the reference entry description.
+    #[must_use]
+    pub fn description(&self) -> &Description
+    {
+        &self.description
+    }
+}
+
+impl FromElements for ReferenceEntry
+{
+    type Error = ReferenceEntryError;
+
+    fn from_elements(elements: &Elements) -> Result<Self, Self::Error>
+    {
+        let refentry_element = elements
+            .get_first_tagged_with_name("refentry")
+            .ok_or(ReferenceEntryError::MissingRefEntry)?;
+
+        let refnamediv_element = refentry_element
+            .child_elements()
+            .get_first_tagged_with_name("refnamediv")
+            .ok_or(ReferenceEntryError::MissingRefNameDiv)?;
+
+        let refpurpose_element = refnamediv_element
+            .child_elements()
+            .get_first_tagged_with_name("refpurpose")
+            .ok_or(ReferenceEntryError::MissingRefPurpose)?;
+
+        let purpose = refpurpose_element
+            .child_elements()
+            .get_first_text_element()
+            .cloned()
+            .unwrap_or_default();
+
+        let description_refsect = refentry_element
+            .child_elements()
+            .get_first_tagged_with_name_and_attr(
+                "refsect1",
+                &Attribute {
+                    key: "xml:id".to_string(),
+                    value: b"description".to_vec(),
+                },
+            )
+            .ok_or(ReferenceEntryError::MissingDescriptionRefSect)?;
+
+        let description =
+            Description::from_elements(description_refsect.child_elements())?;
+
+        Ok(ReferenceEntry {
+            purpose,
+            description,
+        })
+    }
+}
+
+/// [`ReferenceEntry`] error.
+#[derive(Debug, thiserror::Error)]
+pub enum ReferenceEntryError
+{
+    /// No reference entry file was found.
+    #[error("No reference entry file was found for '{0}'")]
+    NoFileFound(String),
+
+    /// No 'refentry' element was found.
+    #[error("No 'refentry' element was found")]
+    MissingRefEntry,
+
+    /// No 'refnamediv' element was found.
+    #[error("No 'refnamediv' element was found")]
+    MissingRefNameDiv,
+
+    /// No 'refpurpose' element was found.
+    #[error("No 'refpurpose' element was found")]
+    MissingRefPurpose,
+
+    /// No 'refsect1' element was found with id 'description''.
+    #[error("No 'refsect1' element was found with id 'description'")]
+    MissingDescriptionRefSect,
+
+    /// Invalid description.
+    #[error("Invalid description")]
+    InvalidDescription(#[from] DescriptionError),
+
+    /// Parsing failed.
+    #[error("Parsing failed")]
+    ParsingFailed(#[from] ParserError),
+}
diff --git a/src/util.rs b/src/util.rs
new file mode 100644
index 0000000..309a471
--- /dev/null
+++ b/src/util.rs
@@ -0,0 +1,34 @@
+macro_rules! enum_with_get_inner {
+    (
+       inner = $inner: ty;
+        $(#[$attr: meta])*
+        $visibility: vis enum $enum_name: ident {
+            $(
+                $(#[$variant_attr: meta])*
+                $variant: ident($variant_inner: ty),
+            )*
+        }
+    ) => {
+        $(#[$attr])*
+        $visibility enum $enum_name {
+            $(
+                $(#[$variant_attr])*
+                $variant($inner)
+            ),*
+        }
+
+        impl $enum_name {
+            /// Returns the inner value.
+            #[must_use]
+            pub fn inner(&self) -> &$inner {
+                match self {
+                    $(
+                        $enum_name::$variant(inner) => inner
+                    ),*
+                }
+            }
+        }
+    };
+}
+
+pub(crate) use enum_with_get_inner;
diff --git a/src/xml/element.rs b/src/xml/element.rs
new file mode 100644
index 0000000..647fe90
--- /dev/null
+++ b/src/xml/element.rs
@@ -0,0 +1,186 @@
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct Elements
+{
+    elements: Vec<Element>,
+}
+
+impl Elements
+{
+    pub fn get_first_tagged(&self) -> Option<&Tagged>
+    {
+        self.elements.iter().find_map(|element| match element {
+            Element::Tagged(tagged_element) => Some(tagged_element),
+            _ => None,
+        })
+    }
+
+    pub fn get_first_tagged_with_name(&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_first_tagged_with_name_and_attr(
+        &self,
+        tag_name: &str,
+        attribute: &Attribute,
+    ) -> Option<&Tagged>
+    {
+        self.elements.iter().find_map(|element| match element {
+            Element::Tagged(tagged_element)
+                if tagged_element.name == tag_name
+                    && tagged_element
+                        .attributes
+                        .iter()
+                        .any(|attr| attr == attribute) =>
+            {
+                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, Clone)]
+pub enum Element
+{
+    Tagged(Tagged),
+    Text(String),
+    Comment(String),
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct Tagged
+{
+    name: String,
+    child_elements: Elements,
+    attributes: Vec<Attribute>,
+}
+
+impl Tagged
+{
+    pub fn new<Name, ChildElements, Attrs>(
+        name: &Name,
+        child_elements: ChildElements,
+        attributes: Attrs,
+    ) -> Self
+    where
+        Name: ToString,
+        ChildElements: Into<Elements>,
+        Attrs: IntoIterator<Item = Attribute>,
+    {
+        Self {
+            name: name.to_string(),
+            child_elements: child_elements.into(),
+            attributes: attributes.into_iter().collect(),
+        }
+    }
+
+    pub fn name(&self) -> &str
+    {
+        &self.name
+    }
+
+    pub fn child_elements(&self) -> &Elements
+    {
+        &self.child_elements
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct Attribute
+{
+    pub key: String,
+    pub value: Vec<u8>,
+}
+
+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..9cdafb1
--- /dev/null
+++ b/src/xml/parser.rs
@@ -0,0 +1,221 @@
+use std::io::BufRead;
+
+use quick_xml::events::attributes::AttrError;
+use quick_xml::events::{BytesStart, BytesText, Event};
+use quick_xml::Reader;
+
+use crate::xml::element::{Attribute, 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(_) => {}
+                },
+            }
+        }
+
+        let attributes = start
+            .attributes()
+            .map(|attr_result| {
+                let attr = attr_result?;
+
+                Ok(Attribute {
+                    key: String::from_utf8(attr.key.as_ref().to_vec())
+                        .map_err(|_| Error::TagAttributeKeyNotUTF8)?,
+                    value: attr.value.into_owned(),
+                })
+            })
+            .collect::<Result<Vec<_>, Error>>()?;
+
+        Ok(Element::Tagged(Tagged::new(
+            &String::from_utf8(start.name().as_ref().to_vec())
+                .map_err(|_| Error::TagNameNotUTF8)?,
+            child_elements,
+            attributes,
+        )))
+    }
+
+    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("Invalid attribute")]
+    InvalidTagAttr(#[from] AttrError),
+
+    #[error("Tag attribute key is not UTF-8")]
+    TagAttributeKeyNotUTF8,
+
+    #[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())],
+                Vec::new()
+            ))])
+        );
+
+        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())]),
+                        Vec::new()
+                    )),
+                    Element::Text(" Hello".to_string())
+                ],
+                Vec::new()
+            ))])
+        );
+
+        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())],
+                        Vec::new()
+                    )),
+                ],
+                Vec::new()
+            ))])
+        );
+    }
+}