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Diffstat (limited to 'vendor/syn/src/stmt.rs')
| -rw-r--r-- | vendor/syn/src/stmt.rs | 452 |
1 files changed, 452 insertions, 0 deletions
diff --git a/vendor/syn/src/stmt.rs b/vendor/syn/src/stmt.rs new file mode 100644 index 0000000..b6d0664 --- /dev/null +++ b/vendor/syn/src/stmt.rs @@ -0,0 +1,452 @@ +use super::*; + +ast_struct! { + /// A braced block containing Rust statements. + #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))] + pub struct Block { + pub brace_token: token::Brace, + /// Statements in a block + pub stmts: Vec<Stmt>, + } +} + +ast_enum! { + /// A statement, usually ending in a semicolon. + #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))] + pub enum Stmt { + /// A local (let) binding. + Local(Local), + + /// An item definition. + Item(Item), + + /// Expression, with or without trailing semicolon. + Expr(Expr, Option<Token![;]>), + + /// A macro invocation in statement position. + /// + /// Syntactically it's ambiguous which other kind of statement this + /// macro would expand to. It can be any of local variable (`let`), + /// item, or expression. + Macro(StmtMacro), + } +} + +ast_struct! { + /// A local `let` binding: `let x: u64 = s.parse()?`. + #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))] + pub struct Local { + pub attrs: Vec<Attribute>, + pub let_token: Token![let], + pub pat: Pat, + pub init: Option<LocalInit>, + pub semi_token: Token![;], + } +} + +ast_struct! { + /// The expression assigned in a local `let` binding, including optional + /// diverging `else` block. + /// + /// `LocalInit` represents `= s.parse()?` in `let x: u64 = s.parse()?` and + /// `= r else { return }` in `let Ok(x) = r else { return }`. + #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))] + pub struct LocalInit { + pub eq_token: Token![=], + pub expr: Box<Expr>, + pub diverge: Option<(Token![else], Box<Expr>)>, + } +} + +ast_struct! { + /// A macro invocation in statement position. + /// + /// Syntactically it's ambiguous which other kind of statement this macro + /// would expand to. It can be any of local variable (`let`), item, or + /// expression. + #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))] + pub struct StmtMacro { + pub attrs: Vec<Attribute>, + pub mac: Macro, + pub semi_token: Option<Token![;]>, + } +} + +#[cfg(feature = "parsing")] +pub(crate) mod parsing { + use super::*; + use crate::parse::discouraged::Speculative as _; + use crate::parse::{Parse, ParseStream, Result}; + use proc_macro2::TokenStream; + + struct AllowNoSemi(bool); + + impl Block { + /// Parse the body of a block as zero or more statements, possibly + /// including one trailing expression. + /// + /// # Example + /// + /// ``` + /// use syn::{braced, token, Attribute, Block, Ident, Result, Stmt, Token}; + /// use syn::parse::{Parse, ParseStream}; + /// + /// // Parse a function with no generics or parameter list. + /// // + /// // fn playground { + /// // let mut x = 1; + /// // x += 1; + /// // println!("{}", x); + /// // } + /// struct MiniFunction { + /// attrs: Vec<Attribute>, + /// fn_token: Token![fn], + /// name: Ident, + /// brace_token: token::Brace, + /// stmts: Vec<Stmt>, + /// } + /// + /// impl Parse for MiniFunction { + /// fn parse(input: ParseStream) -> Result<Self> { + /// let outer_attrs = input.call(Attribute::parse_outer)?; + /// let fn_token: Token![fn] = input.parse()?; + /// let name: Ident = input.parse()?; + /// + /// let content; + /// let brace_token = braced!(content in input); + /// let inner_attrs = content.call(Attribute::parse_inner)?; + /// let stmts = content.call(Block::parse_within)?; + /// + /// Ok(MiniFunction { + /// attrs: { + /// let mut attrs = outer_attrs; + /// attrs.extend(inner_attrs); + /// attrs + /// }, + /// fn_token, + /// name, + /// brace_token, + /// stmts, + /// }) + /// } + /// } + /// ``` + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + pub fn parse_within(input: ParseStream) -> Result<Vec<Stmt>> { + let mut stmts = Vec::new(); + loop { + while let semi @ Some(_) = input.parse()? { + stmts.push(Stmt::Expr(Expr::Verbatim(TokenStream::new()), semi)); + } + if input.is_empty() { + break; + } + let stmt = parse_stmt(input, AllowNoSemi(true))?; + let requires_semicolon = match &stmt { + Stmt::Expr(stmt, None) => expr::requires_terminator(stmt), + Stmt::Macro(stmt) => { + stmt.semi_token.is_none() && !stmt.mac.delimiter.is_brace() + } + Stmt::Local(_) | Stmt::Item(_) | Stmt::Expr(_, Some(_)) => false, + }; + stmts.push(stmt); + if input.is_empty() { + break; + } else if requires_semicolon { + return Err(input.error("unexpected token, expected `;`")); + } + } + Ok(stmts) + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for Block { + fn parse(input: ParseStream) -> Result<Self> { + let content; + Ok(Block { + brace_token: braced!(content in input), + stmts: content.call(Block::parse_within)?, + }) + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for Stmt { + fn parse(input: ParseStream) -> Result<Self> { + let allow_nosemi = AllowNoSemi(false); + parse_stmt(input, allow_nosemi) + } + } + + fn parse_stmt(input: ParseStream, allow_nosemi: AllowNoSemi) -> Result<Stmt> { + let begin = input.fork(); + let attrs = input.call(Attribute::parse_outer)?; + + // brace-style macros; paren and bracket macros get parsed as + // expression statements. + let ahead = input.fork(); + let mut is_item_macro = false; + if let Ok(path) = ahead.call(Path::parse_mod_style) { + if ahead.peek(Token![!]) { + if ahead.peek2(Ident) || ahead.peek2(Token![try]) { + is_item_macro = true; + } else if ahead.peek2(token::Brace) + && !(ahead.peek3(Token![.]) || ahead.peek3(Token![?])) + { + input.advance_to(&ahead); + return stmt_mac(input, attrs, path).map(Stmt::Macro); + } + } + } + + if input.peek(Token![let]) && !input.peek(token::Group) { + stmt_local(input, attrs).map(Stmt::Local) + } else if input.peek(Token![pub]) + || input.peek(Token![crate]) && !input.peek2(Token![::]) + || input.peek(Token![extern]) + || input.peek(Token![use]) + || input.peek(Token![static]) + && (input.peek2(Token![mut]) + || input.peek2(Ident) + && !(input.peek2(Token![async]) + && (input.peek3(Token![move]) || input.peek3(Token![|])))) + || input.peek(Token![const]) + && !(input.peek2(token::Brace) + || input.peek2(Token![static]) + || input.peek2(Token![async]) + && !(input.peek3(Token![unsafe]) + || input.peek3(Token![extern]) + || input.peek3(Token![fn])) + || input.peek2(Token![move]) + || input.peek2(Token![|])) + || input.peek(Token![unsafe]) && !input.peek2(token::Brace) + || input.peek(Token![async]) + && (input.peek2(Token![unsafe]) + || input.peek2(Token![extern]) + || input.peek2(Token![fn])) + || input.peek(Token![fn]) + || input.peek(Token![mod]) + || input.peek(Token![type]) + || input.peek(Token![struct]) + || input.peek(Token![enum]) + || input.peek(Token![union]) && input.peek2(Ident) + || input.peek(Token![auto]) && input.peek2(Token![trait]) + || input.peek(Token![trait]) + || input.peek(Token![default]) + && (input.peek2(Token![unsafe]) || input.peek2(Token![impl])) + || input.peek(Token![impl]) + || input.peek(Token![macro]) + || is_item_macro + { + let item = item::parsing::parse_rest_of_item(begin, attrs, input)?; + Ok(Stmt::Item(item)) + } else { + stmt_expr(input, allow_nosemi, attrs) + } + } + + fn stmt_mac(input: ParseStream, attrs: Vec<Attribute>, path: Path) -> Result<StmtMacro> { + let bang_token: Token![!] = input.parse()?; + let (delimiter, tokens) = mac::parse_delimiter(input)?; + let semi_token: Option<Token![;]> = input.parse()?; + + Ok(StmtMacro { + attrs, + mac: Macro { + path, + bang_token, + delimiter, + tokens, + }, + semi_token, + }) + } + + fn stmt_local(input: ParseStream, attrs: Vec<Attribute>) -> Result<Local> { + let let_token: Token![let] = input.parse()?; + + let mut pat = Pat::parse_single(input)?; + if input.peek(Token![:]) { + let colon_token: Token![:] = input.parse()?; + let ty: Type = input.parse()?; + pat = Pat::Type(PatType { + attrs: Vec::new(), + pat: Box::new(pat), + colon_token, + ty: Box::new(ty), + }); + } + + let init = if let Some(eq_token) = input.parse()? { + let eq_token: Token![=] = eq_token; + let expr: Expr = input.parse()?; + + let diverge = if let Some(else_token) = input.parse()? { + let else_token: Token![else] = else_token; + let diverge = ExprBlock { + attrs: Vec::new(), + label: None, + block: input.parse()?, + }; + Some((else_token, Box::new(Expr::Block(diverge)))) + } else { + None + }; + + Some(LocalInit { + eq_token, + expr: Box::new(expr), + diverge, + }) + } else { + None + }; + + let semi_token: Token![;] = input.parse()?; + + Ok(Local { + attrs, + let_token, + pat, + init, + semi_token, + }) + } + + fn stmt_expr( + input: ParseStream, + allow_nosemi: AllowNoSemi, + mut attrs: Vec<Attribute>, + ) -> Result<Stmt> { + let mut e = expr::parsing::expr_early(input)?; + + let mut attr_target = &mut e; + loop { + attr_target = match attr_target { + Expr::Assign(e) => &mut e.left, + Expr::Binary(e) => &mut e.left, + Expr::Cast(e) => &mut e.expr, + Expr::Array(_) + | Expr::Async(_) + | Expr::Await(_) + | Expr::Block(_) + | Expr::Break(_) + | Expr::Call(_) + | Expr::Closure(_) + | Expr::Const(_) + | Expr::Continue(_) + | Expr::Field(_) + | Expr::ForLoop(_) + | Expr::Group(_) + | Expr::If(_) + | Expr::Index(_) + | Expr::Infer(_) + | Expr::Let(_) + | Expr::Lit(_) + | Expr::Loop(_) + | Expr::Macro(_) + | Expr::Match(_) + | Expr::MethodCall(_) + | Expr::Paren(_) + | Expr::Path(_) + | Expr::Range(_) + | Expr::Reference(_) + | Expr::Repeat(_) + | Expr::Return(_) + | Expr::Struct(_) + | Expr::Try(_) + | Expr::TryBlock(_) + | Expr::Tuple(_) + | Expr::Unary(_) + | Expr::Unsafe(_) + | Expr::While(_) + | Expr::Yield(_) + | Expr::Verbatim(_) => break, + }; + } + attrs.extend(attr_target.replace_attrs(Vec::new())); + attr_target.replace_attrs(attrs); + + let semi_token: Option<Token![;]> = input.parse()?; + + match e { + Expr::Macro(ExprMacro { attrs, mac }) + if semi_token.is_some() || mac.delimiter.is_brace() => + { + return Ok(Stmt::Macro(StmtMacro { + attrs, + mac, + semi_token, + })); + } + _ => {} + } + + if semi_token.is_some() { + Ok(Stmt::Expr(e, semi_token)) + } else if allow_nosemi.0 || !expr::requires_terminator(&e) { + Ok(Stmt::Expr(e, None)) + } else { + Err(input.error("expected semicolon")) + } + } +} + +#[cfg(feature = "printing")] +mod printing { + use super::*; + use proc_macro2::TokenStream; + use quote::{ToTokens, TokenStreamExt}; + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for Block { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.brace_token.surround(tokens, |tokens| { + tokens.append_all(&self.stmts); + }); + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for Stmt { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + Stmt::Local(local) => local.to_tokens(tokens), + Stmt::Item(item) => item.to_tokens(tokens), + Stmt::Expr(expr, semi) => { + expr.to_tokens(tokens); + semi.to_tokens(tokens); + } + Stmt::Macro(mac) => mac.to_tokens(tokens), + } + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for Local { + fn to_tokens(&self, tokens: &mut TokenStream) { + expr::printing::outer_attrs_to_tokens(&self.attrs, tokens); + self.let_token.to_tokens(tokens); + self.pat.to_tokens(tokens); + if let Some(init) = &self.init { + init.eq_token.to_tokens(tokens); + init.expr.to_tokens(tokens); + if let Some((else_token, diverge)) = &init.diverge { + else_token.to_tokens(tokens); + diverge.to_tokens(tokens); + } + } + self.semi_token.to_tokens(tokens); + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for StmtMacro { + fn to_tokens(&self, tokens: &mut TokenStream) { + expr::printing::outer_attrs_to_tokens(&self.attrs, tokens); + self.mac.to_tokens(tokens); + self.semi_token.to_tokens(tokens); + } + } +} |