1 files changed, 313 insertions, 0 deletions
diff --git a/third_party/rust/wast/src/component/component.rs b/third_party/rust/wast/src/component/component.rs
new file mode 100644
index 0000000000..8424e083b8
--- /dev/null
+++ b/third_party/rust/wast/src/component/component.rs
@@ -0,0 +1,313 @@
+use crate::annotation;
+use crate::component::*;
+use crate::kw;
+use crate::parser::{Parse, Parser, Result};
+use crate::token::Index;
+use crate::token::{Id, NameAnnotation, Span};
+
+/// A parsed WebAssembly component module.
+#[derive(Debug)]
+pub struct Component<'a> {
+    /// Where this `component` was defined
+    pub span: Span,
+    /// An optional identifier this component is known by
+    pub id: Option<Id<'a>>,
+    /// An optional `@name` annotation for this component
+    pub name: Option<NameAnnotation<'a>>,
+    /// What kind of component this was parsed as.
+    pub kind: ComponentKind<'a>,
+}
+
+/// The different kinds of ways to define a component.
+#[derive(Debug)]
+pub enum ComponentKind<'a> {
+    /// A component defined in the textual s-expression format.
+    Text(Vec<ComponentField<'a>>),
+    /// A component that had its raw binary bytes defined via the `binary`
+    /// directive.
+    Binary(Vec<&'a [u8]>),
+}
+
+impl<'a> Component<'a> {
+    /// Performs a name resolution pass on this [`Component`], resolving all
+    /// symbolic names to indices.
+    ///
+    /// The WAT format contains a number of shorthands to make it easier to
+    /// write, such as inline exports, inline imports, inline type definitions,
+    /// etc. Additionally it allows using symbolic names such as `$foo` instead
+    /// of using indices. This module will postprocess an AST to remove all of
+    /// this syntactic sugar, preparing the AST for binary emission.  This is
+    /// where expansion and name resolution happens.
+    ///
+    /// This function will mutate the AST of this [`Component`] and replace all
+    /// [`Index`](crate::token::Index) arguments with `Index::Num`. This will
+    /// also expand inline exports/imports listed on fields and handle various
+    /// other shorthands of the text format.
+    ///
+    /// If successful the AST was modified to be ready for binary encoding.
+    ///
+    /// # Errors
+    ///
+    /// If an error happens during resolution, such a name resolution error or
+    /// items are found in the wrong order, then an error is returned.
+    pub fn resolve(&mut self) -> std::result::Result<(), crate::Error> {
+        match &mut self.kind {
+            ComponentKind::Text(fields) => {
+                crate::component::expand::expand(fields);
+            }
+            ComponentKind::Binary(_) => {}
+        }
+        crate::component::resolve::resolve(self)
+    }
+
+    /// Encodes this [`Component`] to its binary form.
+    ///
+    /// This function will take the textual representation in [`Component`] and
+    /// perform all steps necessary to convert it to a binary WebAssembly
+    /// component, suitable for writing to a `*.wasm` file. This function may
+    /// internally modify the [`Component`], for example:
+    ///
+    /// * Name resolution is performed to ensure that `Index::Id` isn't present
+    ///   anywhere in the AST.
+    ///
+    /// * Inline shorthands such as imports/exports/types are all expanded to be
+    ///   dedicated fields of the component.
+    ///
+    /// * Component fields may be shuffled around to preserve index ordering from
+    ///   expansions.
+    ///
+    /// After all of this expansion has happened the component will be converted to
+    /// its binary form and returned as a `Vec<u8>`. This is then suitable to
+    /// hand off to other wasm runtimes and such.
+    ///
+    /// # Errors
+    ///
+    /// This function can return an error for name resolution errors and other
+    /// expansion-related errors.
+    pub fn encode(&mut self) -> std::result::Result<Vec<u8>, crate::Error> {
+        self.resolve()?;
+        Ok(crate::component::binary::encode(self))
+    }
+
+    pub(crate) fn validate(&self, parser: Parser<'_>) -> Result<()> {
+        let mut starts = 0;
+        if let ComponentKind::Text(fields) = &self.kind {
+            for item in fields.iter() {
+                if let ComponentField::Start(_) = item {
+                    starts += 1;
+                }
+            }
+        }
+        if starts > 1 {
+            return Err(parser.error("multiple start sections found"));
+        }
+        Ok(())
+    }
+}
+
+impl<'a> Parse<'a> for Component<'a> {
+    fn parse(parser: Parser<'a>) -> Result<Self> {
+        let _r = parser.register_annotation("custom");
+
+        let span = parser.parse::<kw::component>()?.0;
+        let id = parser.parse()?;
+        let name = parser.parse()?;
+
+        let kind = if parser.peek::<kw::binary>() {
+            parser.parse::<kw::binary>()?;
+            let mut data = Vec::new();
+            while !parser.is_empty() {
+                data.push(parser.parse()?);
+            }
+            ComponentKind::Binary(data)
+        } else {
+            ComponentKind::Text(ComponentField::parse_remaining(parser)?)
+        };
+        Ok(Component {
+            span,
+            id,
+            name,
+            kind,
+        })
+    }
+}
+
+/// A listing of all possible fields that can make up a WebAssembly component.
+#[allow(missing_docs)]
+#[derive(Debug)]
+pub enum ComponentField<'a> {
+    CoreModule(CoreModule<'a>),
+    CoreInstance(CoreInstance<'a>),
+    CoreType(CoreType<'a>),
+    Component(NestedComponent<'a>),
+    Instance(Instance<'a>),
+    Alias(Alias<'a>),
+    Type(Type<'a>),
+    CanonicalFunc(CanonicalFunc<'a>),
+    CoreFunc(CoreFunc<'a>), // Supports inverted forms of other items
+    Func(Func<'a>),         // Supports inverted forms of other items
+    Start(Start<'a>),
+    Import(ComponentImport<'a>),
+    Export(ComponentExport<'a>),
+    Custom(Custom<'a>),
+}
+
+impl<'a> ComponentField<'a> {
+    fn parse_remaining(parser: Parser<'a>) -> Result<Vec<ComponentField>> {
+        let mut fields = Vec::new();
+        while !parser.is_empty() {
+            fields.push(parser.parens(ComponentField::parse)?);
+        }
+        Ok(fields)
+    }
+}
+
+impl<'a> Parse<'a> for ComponentField<'a> {
+    fn parse(parser: Parser<'a>) -> Result<Self> {
+        if parser.peek::<kw::core>() {
+            if parser.peek2::<kw::module>() {
+                return Ok(Self::CoreModule(parser.parse()?));
+            }
+            if parser.peek2::<kw::instance>() {
+                return Ok(Self::CoreInstance(parser.parse()?));
+            }
+            if parser.peek2::<kw::r#type>() {
+                return Ok(Self::CoreType(parser.parse()?));
+            }
+            if parser.peek2::<kw::func>() {
+                return Ok(Self::CoreFunc(parser.parse()?));
+            }
+        } else {
+            if parser.peek::<kw::component>() {
+                return Ok(Self::Component(parser.parse()?));
+            }
+            if parser.peek::<kw::instance>() {
+                return Ok(Self::Instance(parser.parse()?));
+            }
+            if parser.peek::<kw::alias>() {
+                return Ok(Self::Alias(parser.parse()?));
+            }
+            if parser.peek::<kw::r#type>() {
+                return Ok(Self::Type(parser.parse()?));
+            }
+            if parser.peek::<kw::import>() {
+                return Ok(Self::Import(parser.parse()?));
+            }
+            if parser.peek::<kw::func>() {
+                return Ok(Self::Func(parser.parse()?));
+            }
+            if parser.peek::<kw::export>() {
+                return Ok(Self::Export(parser.parse()?));
+            }
+            if parser.peek::<kw::start>() {
+                return Ok(Self::Start(parser.parse()?));
+            }
+            if parser.peek::<annotation::custom>() {
+                return Ok(Self::Custom(parser.parse()?));
+            }
+        }
+        Err(parser.error("expected valid component field"))
+    }
+}
+
+/// A function to call at instantiation time.
+#[derive(Debug)]
+pub struct Start<'a> {
+    /// The function to call.
+    pub func: Index<'a>,
+    /// The arguments to pass to the function.
+    pub args: Vec<ItemRef<'a, kw::value>>,
+    /// Names of the result values.
+    pub results: Vec<Option<Id<'a>>>,
+}
+
+impl<'a> Parse<'a> for Start<'a> {
+    fn parse(parser: Parser<'a>) -> Result<Self> {
+        parser.parse::<kw::start>()?;
+        let func = parser.parse()?;
+        let mut args = Vec::new();
+        while !parser.is_empty() && !parser.peek2::<kw::result>() {
+            args.push(parser.parens(|parser| parser.parse())?);
+        }
+
+        let mut results = Vec::new();
+        while !parser.is_empty() && parser.peek2::<kw::result>() {
+            results.push(parser.parens(|parser| {
+                parser.parse::<kw::result>()?;
+                parser.parens(|parser| {
+                    parser.parse::<kw::value>()?;
+                    parser.parse()
+                })
+            })?);
+        }
+
+        Ok(Start {
+            func,
+            args,
+            results,
+        })
+    }
+}
+
+/// A nested WebAssembly component.
+#[derive(Debug)]
+pub struct NestedComponent<'a> {
+    /// Where this `component` was defined
+    pub span: Span,
+    /// An optional identifier this component is known by
+    pub id: Option<Id<'a>>,
+    /// An optional `@name` annotation for this component
+    pub name: Option<NameAnnotation<'a>>,
+    /// If present, inline export annotations which indicate names this
+    /// definition should be exported under.
+    pub exports: InlineExport<'a>,
+    /// What kind of component this was parsed as.
+    pub kind: NestedComponentKind<'a>,
+}
+
+/// The different kinds of ways to define a nested component.
+#[derive(Debug)]
+pub enum NestedComponentKind<'a> {
+    /// This is actually an inline import of a component
+    Import {
+        /// The information about where this is being imported from.
+        import: InlineImport<'a>,
+        /// The type of component being imported.
+        ty: ComponentTypeUse<'a, ComponentType<'a>>,
+    },
+    /// The component is defined inline as a local definition with its fields
+    /// listed here.
+    Inline(Vec<ComponentField<'a>>),
+}
+
+impl<'a> Parse<'a> for NestedComponent<'a> {
+    fn parse(parser: Parser<'a>) -> Result<Self> {
+        parser.depth_check()?;
+
+        let span = parser.parse::<kw::component>()?.0;
+        let id = parser.parse()?;
+        let name = parser.parse()?;
+        let exports = parser.parse()?;
+
+        let kind = if let Some(import) = parser.parse()? {
+            NestedComponentKind::Import {
+                import,
+                ty: parser.parse()?,
+            }
+        } else {
+            let mut fields = Vec::new();
+            while !parser.is_empty() {
+                fields.push(parser.parens(|p| p.parse())?);
+            }
+            NestedComponentKind::Inline(fields)
+        };
+
+        Ok(NestedComponent {
+            span,
+            id,
+            name,
+            exports,
+            kind,
+        })
+    }
+}