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+/*!
+Frontend for [GLSL][glsl] (OpenGL Shading Language).
+
+To begin, take a look at the documentation for the [`Parser`](Parser).
+
+# Supported versions
+## Vulkan
+- 440 (partial)
+- 450
+- 460
+
+[glsl]: https://www.khronos.org/registry/OpenGL/index_gl.php
+*/
+
+pub use ast::{Precision, Profile};
+pub use error::{Error, ErrorKind, ExpectedToken};
+pub use token::TokenValue;
+
+use crate::{proc::Layouter, FastHashMap, FastHashSet, Handle, Module, ShaderStage, Span, Type};
+use ast::{EntryArg, FunctionDeclaration, GlobalLookup};
+use parser::ParsingContext;
+
+mod ast;
+mod builtins;
+mod constants;
+mod context;
+mod error;
+mod functions;
+mod lex;
+mod offset;
+mod parser;
+#[cfg(test)]
+mod parser_tests;
+mod token;
+mod types;
+mod variables;
+
+type Result<T> = std::result::Result<T, Error>;
+
+/// Per-shader options passed to [`parse`](Parser::parse).
+///
+/// The [`From`](From) trait is implemented for [`ShaderStage`](ShaderStage) to
+/// provide a quick way to create a Options instance.
+/// ```rust
+/// # use naga::ShaderStage;
+/// # use naga::front::glsl::Options;
+/// Options::from(ShaderStage::Vertex);
+/// ```
+#[derive(Debug)]
+pub struct Options {
+ /// The shader stage in the pipeline.
+ pub stage: ShaderStage,
+ /// Preprocesor definitions to be used, akin to having
+ /// ```glsl
+ /// #define key value
+ /// ```
+ /// for each key value pair in the map.
+ pub defines: FastHashMap<String, String>,
+}
+
+impl From<ShaderStage> for Options {
+ fn from(stage: ShaderStage) -> Self {
+ Options {
+ stage,
+ defines: FastHashMap::default(),
+ }
+ }
+}
+
+/// Additional information about the GLSL shader.
+///
+/// Stores additional information about the GLSL shader which might not be
+/// stored in the shader [`Module`](Module).
+#[derive(Debug)]
+pub struct ShaderMetadata {
+ /// The GLSL version specified in the shader trough the use of the
+ /// `#version` preprocessor directive.
+ pub version: u16,
+ /// The GLSL profile specified in the shader trough the use of the
+ /// `#version` preprocessor directive.
+ pub profile: Profile,
+ /// The shader stage in the pipeline, passed to the [`parse`](Parser::parse)
+ /// method via the [`Options`](Options) struct.
+ pub stage: ShaderStage,
+
+ /// The workgroup size for compute shaders, defaults to `[1; 3]` for
+ /// compute shaders and `[0; 3]` for non compute shaders.
+ pub workgroup_size: [u32; 3],
+ /// Whether or not early fragment tests where requested by the shader.
+ /// Defaults to `false`.
+ pub early_fragment_tests: bool,
+
+ /// The shader can request extensions via the
+ /// `#extension` preprocessor directive, in the directive a behavior
+ /// parameter is used to control whether the extension should be disabled,
+ /// warn on usage, enabled if possible or required.
+ ///
+ /// This field only stores extensions which were required or requested to
+ /// be enabled if possible and they are supported.
+ pub extensions: FastHashSet<String>,
+}
+
+impl ShaderMetadata {
+ fn reset(&mut self, stage: ShaderStage) {
+ self.version = 0;
+ self.profile = Profile::Core;
+ self.stage = stage;
+ self.workgroup_size = [if stage == ShaderStage::Compute { 1 } else { 0 }; 3];
+ self.early_fragment_tests = false;
+ self.extensions.clear();
+ }
+}
+
+impl Default for ShaderMetadata {
+ fn default() -> Self {
+ ShaderMetadata {
+ version: 0,
+ profile: Profile::Core,
+ stage: ShaderStage::Vertex,
+ workgroup_size: [0; 3],
+ early_fragment_tests: false,
+ extensions: FastHashSet::default(),
+ }
+ }
+}
+
+/// The `Parser` is the central structure of the GLSL frontend.
+///
+/// To instantiate a new `Parser` the [`Default`](Default) trait is used, so a
+/// call to the associated function [`Parser::default`](Parser::default) will
+/// return a new `Parser` instance.
+///
+/// To parse a shader simply call the [`parse`](Parser::parse) method with a
+/// [`Options`](Options) struct and a [`&str`](str) holding the glsl code.
+///
+/// The `Parser` also provides the [`metadata`](Parser::metadata) to get some
+/// further information about the previously parsed shader, like version and
+/// extensions used (see the documentation for
+/// [`ShaderMetadata`](ShaderMetadata) to see all the returned information)
+///
+/// # Example usage
+/// ```rust
+/// use naga::ShaderStage;
+/// use naga::front::glsl::{Parser, Options};
+///
+/// let glsl = r#"
+/// #version 450 core
+///
+/// void main() {}
+/// "#;
+///
+/// let mut parser = Parser::default();
+/// let options = Options::from(ShaderStage::Vertex);
+/// parser.parse(&options, glsl);
+/// ```
+///
+/// # Reusability
+///
+/// If there's a need to parse more than one shader reusing the same `Parser`
+/// instance may be beneficial since internal allocations will be reused.
+///
+/// Calling the [`parse`](Parser::parse) method multiple times will reset the
+/// `Parser` so no extra care is needed when reusing.
+#[derive(Debug, Default)]
+pub struct Parser {
+ meta: ShaderMetadata,
+
+ lookup_function: FastHashMap<String, FunctionDeclaration>,
+ lookup_type: FastHashMap<String, Handle<Type>>,
+
+ global_variables: Vec<(String, GlobalLookup)>,
+
+ entry_args: Vec<EntryArg>,
+
+ layouter: Layouter,
+
+ errors: Vec<Error>,
+
+ module: Module,
+}
+
+impl Parser {
+ fn reset(&mut self, stage: ShaderStage) {
+ self.meta.reset(stage);
+
+ self.lookup_function.clear();
+ self.lookup_type.clear();
+ self.global_variables.clear();
+ self.entry_args.clear();
+ self.layouter.clear();
+
+ // This is necessary because if the last parsing errored out, the module
+ // wouldn't have been taken
+ self.module = Module::default();
+ }
+
+ /// Parses a shader either outputting a shader [`Module`](Module) or a list
+ /// of [`Error`](Error)s.
+ ///
+ /// Multiple calls using the same `Parser` and different shaders are supported.
+ pub fn parse(
+ &mut self,
+ options: &Options,
+ source: &str,
+ ) -> std::result::Result<Module, Vec<Error>> {
+ self.reset(options.stage);
+
+ let lexer = lex::Lexer::new(source, &options.defines);
+ let mut ctx = ParsingContext::new(lexer);
+
+ if let Err(e) = ctx.parse(self) {
+ self.errors.push(e);
+ }
+
+ if self.errors.is_empty() {
+ Ok(std::mem::take(&mut self.module))
+ } else {
+ Err(std::mem::take(&mut self.errors))
+ }
+ }
+
+ /// Returns additional information about the parsed shader which might not be
+ /// stored in the [`Module`](Module), see the documentation for
+ /// [`ShaderMetadata`](ShaderMetadata) for more information about the
+ /// returned data.
+ ///
+ /// # Notes
+ ///
+ /// Following an unsuccessful parsing the state of the returned information
+ /// is undefined, it might contain only partial information about the
+ /// current shader, the previous shader or both.
+ pub const fn metadata(&self) -> &ShaderMetadata {
+ &self.meta
+ }
+}