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//! Abstract Syntax Tree representation of the Fluent Translation List.
//!
//! The AST of Fluent contains all nodes structures to represent a complete
//! representation of the FTL resource.
//!
//! The tree preserves all semantic information and allow for round-trip
//! of a canonically written FTL resource.
//!
//! The root node is called [`Resource`] and contains a list of [`Entry`] nodes
//! representing all possible entries in the Fluent Translation List.
//!
//! # Example
//!
//! ```
//! use fluent_syntax::parser;
//! use fluent_syntax::ast;
//!
//! let ftl = r#"
//!
//! ## This is a message comment
//! hello-world = Hello World!
//! .tooltip = Tooltip for you, { $userName }.
//!
//! "#;
//!
//! let resource = parser::parse(ftl)
//! .expect("Failed to parse an FTL resource.");
//!
//! assert_eq!(
//! resource.body[0],
//! ast::Entry::Message(
//! ast::Message {
//! id: ast::Identifier {
//! name: "hello-world"
//! },
//! value: Some(ast::Pattern {
//! elements: vec![
//! ast::PatternElement::TextElement {
//! value: "Hello World!"
//! },
//! ]
//! }),
//! attributes: vec![
//! ast::Attribute {
//! id: ast::Identifier {
//! name: "tooltip"
//! },
//! value: ast::Pattern {
//! elements: vec![
//! ast::PatternElement::TextElement {
//! value: "Tooltip for you, "
//! },
//! ast::PatternElement::Placeable {
//! expression: ast::Expression::Inline(
//! ast::InlineExpression::VariableReference {
//! id: ast::Identifier {
//! name: "userName"
//! }
//! }
//! )
//! },
//! ast::PatternElement::TextElement {
//! value: "."
//! },
//! ]
//! }
//! }
//! ],
//! comment: Some(
//! ast::Comment {
//! content: vec!["This is a message comment"]
//! }
//! )
//! }
//! ),
//! );
//! ```
//!
//! ## Errors
//!
//! Fluent AST preserves blocks containing invaid syntax as [`Entry::Junk`].
//!
//! ## White space
//!
//! At the moment, AST does not preserve white space. In result only a
//! canonical form of the AST is suitable for a round-trip.
mod helper;
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
/// Root node of a Fluent Translation List.
///
/// A [`Resource`] contains a body with a list of [`Entry`] nodes.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = "";
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Resource<S> {
pub body: Vec<Entry<S>>,
}
/// A top-level node representing an entry of a [`Resource`].
///
/// Every [`Entry`] is a standalone element and the parser is capable
/// of recovering from errors by identifying a beginning of a next entry.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = Value
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Value"
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
///
/// # Junk Entry
///
/// If FTL source contains invalid FTL content, it will be preserved
/// in form of [`Entry::Junk`] nodes.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// g@rb@ge En!ry
///
/// "#;
///
/// let (resource, _) = parser::parse(ftl)
/// .expect_err("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Junk {
/// content: "g@rb@ge En!ry\n\n"
/// }
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(tag = "type"))]
pub enum Entry<S> {
Message(Message<S>),
Term(Term<S>),
Comment(Comment<S>),
GroupComment(Comment<S>),
ResourceComment(Comment<S>),
Junk { content: S },
}
/// Message node represents the most common [`Entry`] in an FTL [`Resource`].
///
/// A message is a localization unit with a [`Identifier`] unique within a given
/// [`Resource`], and a value or attributes with associated [`Pattern`].
///
/// A message can contain a simple text value, or a compound combination of value
/// and attributes which together can be used to localize a complex User Interface
/// element.
///
/// Finally, each [`Message`] may have an associated [`Comment`].
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// hello-world = Hello, World!
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "hello-world"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Hello, World!"
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// })
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Message<S> {
pub id: Identifier<S>,
pub value: Option<Pattern<S>>,
pub attributes: Vec<Attribute<S>>,
pub comment: Option<Comment<S>>,
}
/// A Fluent [`Term`].
///
/// Terms are semantically similar to [`Message`] nodes, but
/// they represent a separate concept in Fluent system.
///
/// Every term has to have a value, and the parser will
/// report errors when term references are used in wrong positions.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// -brand-name = Nightly
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Term(ast::Term {
/// id: ast::Identifier {
/// name: "brand-name"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Nightly"
/// }
/// ]
/// },
/// attributes: vec![],
/// comment: None,
/// })
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Term<S> {
pub id: Identifier<S>,
pub value: Pattern<S>,
pub attributes: Vec<Attribute<S>>,
pub comment: Option<Comment<S>>,
}
/// Pattern contains a value of a [`Message`], [`Term`] or an [`Attribute`].
///
/// Each pattern is a list of [`PatternElement`] nodes representing
/// either a simple textual value, or a combination of text literals
/// and placeholder [`Expression`] nodes.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// hello-world = Hello, World!
///
/// welcome = Welcome, { $userName }.
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "hello-world"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Hello, World!"
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }),
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "welcome"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Welcome, "
/// },
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::VariableReference {
/// id: ast::Identifier {
/// name: "userName"
/// }
/// }
/// )
/// },
/// ast::PatternElement::TextElement {
/// value: "."
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }),
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Pattern<S> {
pub elements: Vec<PatternElement<S>>,
}
/// PatternElement is an element of a [`Pattern`].
///
/// Each [`PatternElement`] node represents
/// either a simple textual value, or a combination of text literals
/// and placeholder [`Expression`] nodes.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// hello-world = Hello, World!
///
/// welcome = Welcome, { $userName }.
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "hello-world"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Hello, World!"
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }),
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "welcome"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Welcome, "
/// },
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::VariableReference {
/// id: ast::Identifier {
/// name: "userName"
/// }
/// }
/// )
/// },
/// ast::PatternElement::TextElement {
/// value: "."
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }),
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(tag = "type"))]
pub enum PatternElement<S> {
TextElement { value: S },
Placeable { expression: Expression<S> },
}
/// Attribute represents a part of a [`Message`] or [`Term`].
///
/// Attributes are used to express a compound list of keyed
/// [`Pattern`] elements on an entry.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// hello-world =
/// .title = This is a title
/// .accesskey = T
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "hello-world"
/// },
/// value: None,
/// attributes: vec![
/// ast::Attribute {
/// id: ast::Identifier {
/// name: "title"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "This is a title"
/// },
/// ]
/// }
/// },
/// ast::Attribute {
/// id: ast::Identifier {
/// name: "accesskey"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "T"
/// },
/// ]
/// }
/// }
/// ],
/// comment: None,
/// }),
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Attribute<S> {
pub id: Identifier<S>,
pub value: Pattern<S>,
}
/// Identifier is part of nodes such as [`Message`], [`Term`] and [`Attribute`].
///
/// It is used to associate a unique key with an [`Entry`] or an [`Attribute`]
/// and in [`Expression`] nodes to refer to another entry.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// hello-world = Value
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "hello-world"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Value"
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }),
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Identifier<S> {
pub name: S,
}
/// Variant is a single branch of a value in a [`Select`](Expression::Select) expression.
///
/// It's a pair of [`VariantKey`] and [`Pattern`]. If the selector match the
/// key, then the value of the variant is returned as the value of the expression.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// hello-world = { $var ->
/// [key1] Value 1
/// *[other] Value 2
/// }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "hello-world"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Select {
/// selector: ast::InlineExpression::VariableReference {
/// id: ast::Identifier { name: "var" },
/// },
/// variants: vec![
/// ast::Variant {
/// key: ast::VariantKey::Identifier {
/// name: "key1"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Value 1",
/// }
/// ]
/// },
/// default: false,
/// },
/// ast::Variant {
/// key: ast::VariantKey::Identifier {
/// name: "other"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Value 2",
/// }
/// ]
/// },
/// default: true,
/// },
/// ]
/// }
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }),
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(tag = "type"))]
pub struct Variant<S> {
pub key: VariantKey<S>,
pub value: Pattern<S>,
pub default: bool,
}
/// A key of a [`Variant`].
///
/// Variant key can be either an identifier or a number.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// hello-world = { $var ->
/// [0] Value 1
/// *[other] Value 2
/// }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "hello-world"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Select {
/// selector: ast::InlineExpression::VariableReference {
/// id: ast::Identifier { name: "var" },
/// },
/// variants: vec![
/// ast::Variant {
/// key: ast::VariantKey::NumberLiteral {
/// value: "0"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Value 1",
/// }
/// ]
/// },
/// default: false,
/// },
/// ast::Variant {
/// key: ast::VariantKey::Identifier {
/// name: "other"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Value 2",
/// }
/// ]
/// },
/// default: true,
/// },
/// ]
/// }
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }),
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(tag = "type"))]
pub enum VariantKey<S> {
Identifier { name: S },
NumberLiteral { value: S },
}
/// Fluent [`Comment`].
///
/// In Fluent, comments may be standalone, or associated with
/// an entry such as [`Term`] or [`Message`].
///
/// When used as a standalone [`Entry`], comments may appear in one of
/// three levels:
///
/// * Standalone comment
/// * Group comment associated with a group of messages
/// * Resource comment associated with the whole resource
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
/// ## A standalone level comment
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Comment(ast::Comment {
/// content: vec![
/// "A standalone level comment"
/// ]
/// })
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(from = "helper::CommentDef<S>"))]
pub struct Comment<S> {
pub content: Vec<S>,
}
/// List of arguments for a [`FunctionReference`](InlineExpression::FunctionReference) or a
/// [`TermReference`](InlineExpression::TermReference).
///
/// Function and Term reference may contain a list of positional and
/// named arguments passed to them.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { FUNC($var1, "literal", style: "long") }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::FunctionReference {
/// id: ast::Identifier {
/// name: "FUNC"
/// },
/// arguments: ast::CallArguments {
/// positional: vec![
/// ast::InlineExpression::VariableReference {
/// id: ast::Identifier {
/// name: "var1"
/// }
/// },
/// ast::InlineExpression::StringLiteral {
/// value: "literal",
/// }
/// ],
/// named: vec![
/// ast::NamedArgument {
/// name: ast::Identifier {
/// name: "style"
/// },
/// value: ast::InlineExpression::StringLiteral
/// {
/// value: "long"
/// }
/// }
/// ],
/// }
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone, Default)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(tag = "type"))]
pub struct CallArguments<S> {
pub positional: Vec<InlineExpression<S>>,
pub named: Vec<NamedArgument<S>>,
}
/// A key-value pair used in [`CallArguments`].
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { FUNC(style: "long") }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::FunctionReference {
/// id: ast::Identifier {
/// name: "FUNC"
/// },
/// arguments: ast::CallArguments {
/// positional: vec![],
/// named: vec![
/// ast::NamedArgument {
/// name: ast::Identifier {
/// name: "style"
/// },
/// value: ast::InlineExpression::StringLiteral
/// {
/// value: "long"
/// }
/// }
/// ],
/// }
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(tag = "type"))]
pub struct NamedArgument<S> {
pub name: Identifier<S>,
pub value: InlineExpression<S>,
}
/// A subset of expressions which can be used as [`Placeable`](PatternElement::Placeable),
/// [`selector`](Expression::Select), or in [`CallArguments`].
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { $emailCount }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::VariableReference {
/// id: ast::Identifier {
/// name: "emailCount"
/// },
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(tag = "type"))]
pub enum InlineExpression<S> {
/// Single line string literal enclosed in `"`.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { "this is a literal" }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::StringLiteral {
/// value: "this is a literal",
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
StringLiteral { value: S },
/// A number literal.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { -0.5 }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::NumberLiteral {
/// value: "-0.5",
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
NumberLiteral { value: S },
/// A function reference.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { FUNC() }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::FunctionReference {
/// id: ast::Identifier {
/// name: "FUNC"
/// },
/// arguments: ast::CallArguments::default(),
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
FunctionReference {
id: Identifier<S>,
arguments: CallArguments<S>,
},
/// A reference to another message.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { key2 }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::MessageReference {
/// id: ast::Identifier {
/// name: "key2"
/// },
/// attribute: None,
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
MessageReference {
id: Identifier<S>,
attribute: Option<Identifier<S>>,
},
/// A reference to a term.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { -brand-name }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::TermReference {
/// id: ast::Identifier {
/// name: "brand-name"
/// },
/// attribute: None,
/// arguments: None,
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
TermReference {
id: Identifier<S>,
attribute: Option<Identifier<S>>,
arguments: Option<CallArguments<S>>,
},
/// A reference to a variable.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { $var1 }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::VariableReference {
/// id: ast::Identifier {
/// name: "var1"
/// },
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
VariableReference { id: Identifier<S> },
/// A placeable which may contain another expression.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { { "placeable" } }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(
/// ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Inline(
/// ast::InlineExpression::Placeable {
/// expression: Box::new(
/// ast::Expression::Inline(
/// ast::InlineExpression::StringLiteral {
/// value: "placeable"
/// }
/// )
/// )
/// }
/// )
/// },
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }
/// )
/// ]
/// }
/// );
/// ```
Placeable { expression: Box<Expression<S>> },
}
/// An expression that is either a select expression or an inline expression.
///
/// # Example
///
/// ```
/// use fluent_syntax::parser;
/// use fluent_syntax::ast;
///
/// let ftl = r#"
///
/// key = { $var ->
/// [key1] Value 1
/// *[other] Value 2
/// }
///
/// "#;
///
/// let resource = parser::parse(ftl)
/// .expect("Failed to parse an FTL resource.");
///
/// assert_eq!(
/// resource,
/// ast::Resource {
/// body: vec![
/// ast::Entry::Message(ast::Message {
/// id: ast::Identifier {
/// name: "key"
/// },
/// value: Some(ast::Pattern {
/// elements: vec![
/// ast::PatternElement::Placeable {
/// expression: ast::Expression::Select {
/// selector: ast::InlineExpression::VariableReference {
/// id: ast::Identifier { name: "var" },
/// },
/// variants: vec![
/// ast::Variant {
/// key: ast::VariantKey::Identifier {
/// name: "key1"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Value 1",
/// }
/// ]
/// },
/// default: false,
/// },
/// ast::Variant {
/// key: ast::VariantKey::Identifier {
/// name: "other"
/// },
/// value: ast::Pattern {
/// elements: vec![
/// ast::PatternElement::TextElement {
/// value: "Value 2",
/// }
/// ]
/// },
/// default: true,
/// },
/// ]
/// }
/// }
/// ]
/// }),
/// attributes: vec![],
/// comment: None,
/// }),
/// ]
/// }
/// );
/// ```
#[derive(Debug, PartialEq, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(untagged))]
pub enum Expression<S> {
Select {
selector: InlineExpression<S>,
variants: Vec<Variant<S>>,
},
Inline(InlineExpression<S>),
}