parser/
stmt.rs

1use crate::try_parse;
2use dynamic::{Dynamic, Type};
3
4use super::{Expr, Parser, Pattern, Span, expr::ExprKind, pattern::PatternKind};
5use anyhow::{Result, anyhow};
6use smol_str::SmolStr;
7
8/// 把 pattern 引入的所有变量绑定生成出来,追加到 `out`。
9/// `access` 是该 pattern 整体对应的访问表达式(如 `__m_scrut` 或 `__m_scrut.field`)。
10fn collect_bindings(pat: &Pattern, access: &Expr, out: &mut Vec<Stmt>, span: Span) {
11    use crate::expr::BinaryOp;
12    let mk_let_ident = |name: SmolStr, value: Expr, span: Span| {
13        let p = Pattern::new(PatternKind::Ident { name, ty: Type::Any }, span);
14        let value_stmt = Stmt::new(StmtKind::Expr(value, true), span);
15        Stmt::new(StmtKind::Let { pat: p, value: Box::new(value_stmt) }, span)
16    };
17    let mk_bin = |left: Expr, op: BinaryOp, right: Expr, span: Span| Expr::new(ExprKind::Binary { left: Box::new(left), op, right: Box::new(right) }, span);
18    let mk_idx_int = |obj: Expr, i: i32, span: Span| mk_bin(obj, BinaryOp::Idx, Expr::new(ExprKind::Value(Dynamic::I32(i)), span), span);
19    let mk_field = |obj: Expr, name: SmolStr, span: Span| mk_bin(obj, BinaryOp::Idx, Expr::new(ExprKind::Value(Dynamic::String(name)), span), span);
20
21    match &pat.kind {
22        PatternKind::Ident { name, .. } => {
23            out.push(mk_let_ident(name.clone(), access.clone(), span));
24        }
25        PatternKind::Tuple(items) => {
26            for (i, p) in items.iter().enumerate() {
27                let elem = mk_idx_int(access.clone(), i as i32, span);
28                collect_bindings(p, &elem, out, span);
29            }
30        }
31        PatternKind::List { elems, has_rest } => {
32            let prefix = if *has_rest { elems.len() - 1 } else { elems.len() };
33            for (i, p) in elems.iter().take(prefix).enumerate() {
34                let elem = mk_idx_int(access.clone(), i as i32, span);
35                collect_bindings(p, &elem, out, span);
36            }
37            if *has_rest {
38                if let PatternKind::Ident { name, .. } = &elems.last().unwrap().kind {
39                    // 切片: access[prefix..];用 `ExprKind::Range` 而不是 `Binary{RangeOpen}`,
40                    // 与 parser 产物一致,这样下游 type infer / 优化都走同一条路径。
41                    let from = Expr::new(ExprKind::Value((prefix as u32).into()), span);
42                    let range = Expr::new(ExprKind::Range { start: Box::new(from), stop: Box::new(Expr::new(ExprKind::Value(Dynamic::Null), span)), inclusive: false }, span);
43                    let slice = Expr::new(ExprKind::Binary { left: Box::new(access.clone()), op: BinaryOp::Idx, right: Box::new(range) }, span);
44                    out.push(mk_let_ident(name.clone(), slice, span));
45                }
46            }
47        }
48        PatternKind::Struct { fields, .. } => {
49            for (fname, sub) in fields {
50                let field_access = mk_field(access.clone(), fname.clone(), span);
51                match sub {
52                    None => {
53                        // 简写 `field` —— 绑定同名变量
54                        out.push(mk_let_ident(fname.clone(), field_access, span));
55                    }
56                    Some(sub_pat) => {
57                        collect_bindings(sub_pat, &field_access, out, span);
58                    }
59                }
60            }
61        }
62        // 其它(Wildcard / Literal / Var / Member / Idx)在 match 上下文中不产生绑定
63        _ => {}
64    }
65}
66
67#[derive(Debug, Clone)]
68pub struct Stmt {
69    pub kind: StmtKind,
70    pub span: Span,
71}
72
73#[derive(Debug, Clone)]
74pub enum StmtKind {
75    Let { pat: Pattern, value: Box<Stmt> },
76    Expr(Expr, bool),
77    Block(Vec<Stmt>),
78    Break,
79    Continue,
80    Return(Option<Expr>),
81    While { cond: Expr, body: Box<Stmt> },
82    Loop(Box<Stmt>),
83    For { pat: Pattern, range: Expr, body: Box<Stmt> },
84    Fn { name: SmolStr, generic_params: Vec<Type>, args: Vec<(SmolStr, Type)>, body: Box<Stmt>, is_pub: bool },
85    Struct { name: SmolStr, def: Type, is_pub: bool },
86    Impl { target: Type, body: Box<Stmt> },
87    If { cond: Expr, then_body: Box<Stmt>, else_body: Option<Box<Stmt>> },
88    Static { name: SmolStr, ty: Type, value: Option<Expr>, is_pub: bool },
89    Const { name: SmolStr, ty: Type, value: Expr, is_pub: bool },
90}
91
92impl Stmt {
93    pub fn new(kind: StmtKind, span: Span) -> Self {
94        Self { kind, span }
95    }
96
97    pub fn expr(&self) -> Option<Expr> {
98        if let StmtKind::Expr(expr, _) = &self.kind { Some(expr.clone()) } else { None }
99    }
100
101    pub fn is_return(&self) -> bool {
102        matches!(self.kind, StmtKind::Return(_))
103    }
104
105    pub fn last_return(&mut self) -> bool {
106        match &mut self.kind {
107            StmtKind::Block(stmts) => stmts.last_mut().map(|stmt| stmt.last_return()).unwrap_or(false),
108            StmtKind::If { then_body, else_body, .. } => {
109                let then_returns = then_body.last_return();
110                let else_returns = else_body.as_mut().map(|body| body.last_return()).unwrap_or(false);
111                then_returns && else_returns
112            }
113            StmtKind::Expr(e, close) => {
114                if !*close {
115                    let span = e.span;
116                    *self = Self::new(StmtKind::Return(Some(std::mem::take(e))), span);
117                    true
118                } else {
119                    false
120                }
121            }
122            StmtKind::Return(_) => true,
123            _ => false,
124        }
125    }
126
127    pub fn get_type(&self) -> Option<Type> {
128        match &self.kind {
129            StmtKind::Expr(expr, _) => Some(expr.get_type()),
130            StmtKind::Block(stmts) => stmts.last().and_then(|stmt| stmt.get_type()),
131            StmtKind::If { then_body, .. } => then_body.get_type(),
132            _ => None,
133        }
134    }
135
136    fn get_assign(idx: u32, expr: Expr) -> Self {
137        let span = expr.span;
138        Self::new(StmtKind::Expr(Expr::new(ExprKind::Binary { left: Box::new(Expr::new(ExprKind::Var(idx), span)), op: crate::BinaryOp::Assign, right: Box::new(expr) }, span), true), span)
139    }
140
141    fn get_idx_assign(pat: Expr, idx: usize, expr: Expr) -> Self {
142        let span = pat.span.merge(expr.span);
143        let right = Expr::new(ExprKind::Binary { left: Box::new(expr), op: crate::BinaryOp::Idx, right: Box::new(Expr::new(ExprKind::Value((idx as u32).into()), span)) }, span);
144        Self::new(StmtKind::Expr(Expr::new(ExprKind::Binary { left: Box::new(pat), op: crate::BinaryOp::Assign, right: Box::new(right) }, span), true), span)
145    }
146
147    fn get_assign_expr(pat: Expr, expr: Expr) -> Self {
148        let span = pat.span.merge(expr.span);
149        Self::new(StmtKind::Expr(Expr::new(ExprKind::Binary { left: Box::new(pat), op: crate::BinaryOp::Assign, right: Box::new(expr) }, span), true), span)
150    }
151
152    pub fn bind_pattern(&mut self, pat: Pattern) -> Result<()> {
153        if let Some(expr) = self.expr() {
154            let stmt = match pat.kind {
155                PatternKind::Var { idx, ty } => {
156                    if expr.get_type() != ty {
157                        Self::get_assign(idx, Expr::new(ExprKind::Typed { value: Box::new(expr), ty }, pat.span))
158                    } else {
159                        Self::get_assign(idx, expr)
160                    }
161                }
162                PatternKind::Tuple(list) => {
163                    let mut stmts = Vec::new();
164                    for (idx, p) in list.into_iter().enumerate() {
165                        match p.expr() {
166                            Ok(p) => stmts.push(Self::get_idx_assign(p, idx, expr.clone())),
167                            Err(e) => return Err(e),
168                        }
169                    }
170                    Self::new(StmtKind::Block(stmts), self.span)
171                }
172                PatternKind::List { elems, has_rest } => {
173                    let mut stmts = Vec::new();
174                    let prefix_count = if has_rest { elems.len() - 1 } else { elems.len() };
175                    for (idx, p) in elems.iter().take(prefix_count).enumerate() {
176                        match p.expr() {
177                            Ok(p) => stmts.push(Self::get_idx_assign(p, idx, expr.clone())),
178                            Err(e) => return Err(e),
179                        }
180                    }
181                    if has_rest {
182                        // 最后一个元素是 `..rest`,把它绑定为 expr[prefix_count..] 的切片。
183                        let rest_pat = elems.last().unwrap();
184                        let rest_expr = match &rest_pat.kind {
185                            PatternKind::Ident { name, .. } => Expr::new(ExprKind::Ident(name.clone()), rest_pat.span),
186                            PatternKind::Var { idx, .. } => Expr::new(ExprKind::Var(*idx), rest_pat.span),
187                            _ => return Err(anyhow!("..rest 后的模式必须是标识符")),
188                        };
189                        let from = Expr::new(ExprKind::Value((prefix_count as u32).into()), rest_pat.span);
190                        // 用 `ExprKind::Range` 与 parser 产物对齐,确保下游 type infer 走切片分支。
191                        let range = Expr::new(ExprKind::Range { start: Box::new(from), stop: Box::new(Expr::new(ExprKind::Value(Dynamic::Null), rest_pat.span)), inclusive: false }, rest_pat.span);
192                        let slice_idx = Expr::new(ExprKind::Binary { left: Box::new(expr.clone()), op: crate::BinaryOp::Idx, right: Box::new(range) }, rest_pat.span);
193                        stmts.push(Self::get_assign_expr(rest_expr, slice_idx));
194                    }
195                    Self::new(StmtKind::Block(stmts), self.span)
196                }
197                p => return Err(anyhow!("不支持的模式绑定: {:?}", p)),
198            };
199            let _ = std::mem::replace(self, stmt);
200        } else {
201            match &mut self.kind {
202                StmtKind::Block(stmts) => {
203                    if let Some(stmt) = stmts.last_mut() {
204                        stmt.bind_pattern(pat)?;
205                    }
206                }
207                StmtKind::If { then_body, else_body, .. } => {
208                    then_body.bind_pattern(pat.clone())?;
209                    if let Some(e) = else_body {
210                        e.bind_pattern(pat)?;
211                    }
212                }
213                _ => {}
214            }
215        }
216        Ok(())
217    }
218}
219
220use std::fmt;
221impl fmt::Display for Stmt {
222    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
223        match &self.kind {
224            StmtKind::Let { pat, value } => writeln!(f, "let {:?} = {}", pat, value)?,
225            StmtKind::Block(stmts) => stmts.iter().for_each(|s| {
226                let _ = write!(f, "{}", s);
227            }),
228            StmtKind::Expr(expr, close) => writeln!(f, "{:?}[{}]", expr, close)?,
229            StmtKind::Break => writeln!(f, "break")?,
230            StmtKind::Continue => writeln!(f, "continue")?,
231            StmtKind::Return(r) => writeln!(f, "return {:?}", r)?,
232            StmtKind::While { cond, body } => write!(f, "while {:?}\n{}", cond, body)?,
233            StmtKind::Loop(body) => write!(f, "loop\n{}", body)?,
234            StmtKind::For { pat, range, body } => writeln!(f, "for {:?} in {:?} \n{}", pat, range, body)?,
235            StmtKind::If { cond, then_body, else_body } => {
236                write!(f, "if {:?}\nthen-> {}\n", cond, then_body)?;
237                if let Some(e) = else_body {
238                    writeln!(f, "{}", e)?;
239                }
240            }
241            StmtKind::Fn { name, generic_params, args, body, is_pub } => {
242                let generic_suffix = if generic_params.is_empty() { String::new() } else { format!("<{:?}>", generic_params) };
243                if *is_pub {
244                    write!(f, "pub fn {:?}{} {:?}\n", name, generic_suffix, args)?
245                } else {
246                    write!(f, "fn {:?}{} {:?}\n", name, generic_suffix, args)?
247                }
248                write!(f, "{}", body)?;
249            }
250            _ => write!(f, "(todo display: {:?})", self.kind)?,
251        }
252        fmt::Result::Ok(())
253    }
254}
255
256impl Parser {
257    pub fn ident_typed(&mut self) -> Result<(SmolStr, Type)> {
258        let name = self.ident()?;
259        self.whitespace()?;
260        if self.take(b':').is_ok() { Ok((name, self.get_type()?)) } else { Ok((name, Type::Any)) }
261    }
262
263    pub fn ident_generic(&mut self) -> Result<(SmolStr, Vec<Type>)> {
264        self.whitespace()?;
265        let name = self.ident()?;
266        self.whitespace()?;
267        let params = if self.get()? == b'<' {
268            self.pos += 1;
269            crate::parse_list!(self, Vec::new(), b'>', b',', self.get_type_param()?)
270        } else {
271            Vec::new()
272        };
273        Ok((name, params))
274    }
275
276    pub fn block(&mut self) -> Result<Stmt> {
277        self.check_fatal()?;
278        self.whitespace()?;
279        let start = self.current_pos();
280        if self.get()? == b'{' {
281            self.pos += 1;
282            self.enter_depth()?;
283            self.push_decl_scope();
284            let result = (|| -> Result<Stmt> {
285                let body = crate::parse_list!(self, Vec::new(), b'}', 0, self.stmt(false)?);
286                Ok(Stmt::new(StmtKind::Block(body), self.span_from(start)))
287            })();
288            self.pop_decl_scope();
289            self.exit_depth();
290            result
291        } else {
292            Err(anyhow!("not code block"))
293        }
294    }
295
296    pub fn if_block(&mut self) -> Result<Stmt> {
297        let start = self.spans.last().copied().unwrap_or_else(|| self.current_pos());
298        let cond = self.get_expr_without_struct_literal()?;
299        let then_body = Box::new(self.block()?);
300        self.whitespace()?;
301        let else_body = if self.keyword("else").is_ok() {
302            self.whitespace()?;
303            let body = if self.keyword("if").is_ok() { self.if_block()? } else { self.block()? };
304            Some(Box::new(body))
305        } else {
306            None
307        };
308        Ok(Stmt::new(StmtKind::If { cond, then_body, else_body }, Span::new(start, self.current_pos())))
309    }
310
311    /// 解析 `match scrut { pat ("|" pat)* ("if" guard)? => body ","? ... }`,
312    /// desugar 成 `Block + Let + If 链 + 临时变量`,返回顶层 `Block`(再由
313    /// 调用方用 `ExprKind::Stmt` 包成表达式)。
314    pub fn match_block(&mut self, start: usize) -> Result<Stmt> {
315        use crate::expr::{BinaryOp, ExprKind, UnaryOp};
316        use crate::pattern::{Pattern, PatternKind};
317
318        // ---- 一、解析阶段 ----
319        let scrut = self.get_expr_without_struct_literal()?;
320        self.whitespace()?;
321        self.take(b'{').map_err(|_| anyhow!("match 缺少 `{{`"))?;
322
323        // 每个 arm 是 (pats: Vec<Pattern>, guard: Option<Expr>, body: Expr)
324        let mut arms: Vec<(Vec<Pattern>, Option<Expr>, Expr)> = Vec::new();
325        loop {
326            self.whitespace()?;
327            if self.take(b'}').is_ok() {
328                break;
329            }
330            self.push_decl_scope();
331            let arm_res: Result<(Vec<Pattern>, Option<Expr>, Expr)> = (|| {
332                // 一组 pattern(用 `|` 分隔,or-pattern)
333                let mut pats = vec![self.pattern()?];
334                self.whitespace()?;
335                while matches!(self.get(), Ok(b'|')) && !matches!(self.ahead(), Ok(b'|')) {
336                    self.pos += 1;
337                    self.whitespace()?;
338                    pats.push(self.pattern()?);
339                    self.whitespace()?;
340                }
341                // 声明 pattern 引入的变量(对每个 alt 都声明,允许重名 → 由
342                // declare_symbol_in_current_scope 容错;这里我们只用第一个 alt 的 binding)
343                for pat in &pats[..1] {
344                    self.declare_pattern_symbols(pat)?;
345                }
346                // 校验 or-pattern:第二及之后必须是 Literal(MVP 限制)
347                if pats.len() > 1 {
348                    for p in &pats[1..] {
349                        if !matches!(p.kind, PatternKind::Literal(_) | PatternKind::Wildcard) {
350                            return Err(anyhow!("or-pattern 中除第一个外只支持字面量 / 通配模式 (MVP 限制)"));
351                        }
352                    }
353                }
354                // 可选 guard
355                self.whitespace()?;
356                let guard = if self.keyword("if").is_ok() {
357                    self.whitespace()?;
358                    Some(self.get_expr_no_assign()?)
359                } else {
360                    None
361                };
362                // `=>`
363                self.whitespace()?;
364                self.just("=>").map_err(|_| anyhow!("match arm 缺少 `=>`"))?;
365                self.whitespace()?;
366                // 体
367                let body_start = self.current_pos();
368                let body = if self.get()? == b'{' {
369                    let block_stmt = self.block()?;
370                    Expr::new(ExprKind::Stmt(Box::new(block_stmt)), Span::new(body_start, self.current_pos()))
371                } else {
372                    // body 也用 no_assign 防止 `=> body, ...` 中 `,` 后或下一 arm
373                    // 的 `=>` 被错误吞入(同时仍允许 +-*/ 等正常二元)。
374                    self.get_expr_no_assign()?
375                };
376                // 容忍尾随逗号
377                self.whitespace()?;
378                let _ = self.take(b',');
379                Ok((pats, guard, body))
380            })();
381            self.pop_decl_scope();
382            arms.push(arm_res?);
383        }
384        let span = Span::new(start, self.current_pos());
385
386        // ---- 二、声明 match 顶层临时变量 ----
387        // 为避免嵌套 match 重名,加 counter 后缀(简单递增,parser 本地状态)
388        let suffix = self.match_counter;
389        self.match_counter += 1;
390        let scrut_name: SmolStr = format!("__m_scrut_{}", suffix).into();
391        let done_name: SmolStr = format!("__m_done_{}", suffix).into();
392        let out_name: SmolStr = format!("__m_out_{}", suffix).into();
393        self.declare_symbol_in_current_scope(&scrut_name)?;
394        self.declare_symbol_in_current_scope(&done_name)?;
395        self.declare_symbol_in_current_scope(&out_name)?;
396
397        // ---- 三、构建顶层 Block ----
398        let mk_ident = |name: &SmolStr, span: Span| Expr::new(ExprKind::Ident(name.clone()), span);
399        let mk_value = |v: Dynamic, span: Span| Expr::new(ExprKind::Value(v), span);
400        let mk_binary = |left: Expr, op: BinaryOp, right: Expr, span: Span| Expr::new(ExprKind::Binary { left: Box::new(left), op, right: Box::new(right) }, span);
401        let mk_let = |name: SmolStr, value: Expr, span: Span| {
402            let pat = Pattern::new(PatternKind::Ident { name, ty: Type::Any }, span);
403            let value_stmt = Stmt::new(StmtKind::Expr(value, true), span);
404            Stmt::new(StmtKind::Let { pat, value: Box::new(value_stmt) }, span)
405        };
406        let mk_assign_stmt = |name: &SmolStr, value: Expr, span: Span| {
407            let assign = mk_binary(mk_ident(name, span), BinaryOp::Assign, value, span);
408            Stmt::new(StmtKind::Expr(assign, true), span)
409        };
410
411        let mut stmts = Vec::new();
412        // let __m_scrut = SCRUT;
413        stmts.push(mk_let(scrut_name.clone(), scrut, span));
414        // let __m_done = false;
415        stmts.push(mk_let(done_name.clone(), mk_value(Dynamic::Bool(false), span), span));
416        // let __m_out = null;
417        stmts.push(mk_let(out_name.clone(), mk_value(Dynamic::Null, span), span));
418
419        // 每个 arm 一个 if(顺序构造)
420        for (pats, guard, body) in arms {
421            let arm_span = body.span;
422            let scrut_ident = mk_ident(&scrut_name, arm_span);
423            // test = pat[0].test || pat[1].test || ...
424            let mut test_chain = pats[0].match_test(&scrut_ident);
425            for p in &pats[1..] {
426                let t = p.match_test(&scrut_ident);
427                test_chain = mk_binary(test_chain, BinaryOp::Or, t, arm_span);
428            }
429            // !__m_done && (test_chain)
430            let not_done = Expr::new(ExprKind::Unary { op: UnaryOp::Not, value: Box::new(mk_ident(&done_name, arm_span)) }, arm_span);
431            let outer_cond = mk_binary(not_done, BinaryOp::And, test_chain, arm_span);
432
433            // arm body block:bind + guard + assign + done
434            let mut body_stmts = Vec::new();
435            collect_bindings(&pats[0], &mk_ident(&scrut_name, arm_span), &mut body_stmts, arm_span);
436            // 内层 body:__m_out = BODY; __m_done = true;
437            let inner_stmts = vec![mk_assign_stmt(&out_name, body, arm_span), mk_assign_stmt(&done_name, mk_value(Dynamic::Bool(true), arm_span), arm_span)];
438            let inner_block = Stmt::new(StmtKind::Block(inner_stmts), arm_span);
439            // 如果有 guard,再裹一层 if;否则直接展开
440            if let Some(g) = guard {
441                body_stmts.push(Stmt::new(StmtKind::If { cond: g, then_body: Box::new(inner_block), else_body: None }, arm_span));
442            } else {
443                body_stmts.push(inner_block);
444            }
445            let then_body = Stmt::new(StmtKind::Block(body_stmts), arm_span);
446            stmts.push(Stmt::new(StmtKind::If { cond: outer_cond, then_body: Box::new(then_body), else_body: None }, arm_span));
447        }
448        // 末尾求值:__m_out
449        stmts.push(Stmt::new(StmtKind::Expr(mk_ident(&out_name, span), false), span));
450
451        Ok(Stmt::new(StmtKind::Block(stmts), span))
452    }
453
454    pub fn stmt(&mut self, is_pub: bool) -> Result<Stmt> {
455        self.check_fatal()?;
456        self.whitespace()?;
457        self.spans.push(self.pos);
458        let start = self.current_pos();
459        // 函数体内不允许 fn / struct / impl / const / static 顶层声明。
460        // 编译器对这些位置直接 panic，这里前置到 parser，让错误落到用户可见的地方。
461        if self.fn_body_depth > 0 {
462            for kw in &["fn", "struct", "impl", "const", "static"] {
463                if self.keyword(kw).is_ok() {
464                    return Err(anyhow!("函数体内不能定义 {}；请移到顶层或改用闭包", kw));
465                }
466            }
467        }
468        // impl body 允许 fn(方法)和 pub fn,但拒绝嵌套 struct / impl / const / static。
469        if self.impl_body_depth > 0 {
470            for kw in &["struct", "impl", "const", "static"] {
471                if self.keyword(kw).is_ok() {
472                    return Err(anyhow!("impl 体内不能定义 {}；请移到顶层", kw));
473                }
474            }
475        }
476        let stmt = if self.keyword("let").is_ok() {
477            let pat = self.pattern()?;
478            self.declare_pattern_symbols(&pat)?;
479            self.until(b'=')?;
480            self.whitespace()?;
481            let value = if self.get()? == b'{' {
482                if self.looks_like_dict() {
483                    self.get_expr()?
484                } else {
485                    // 块作为表达式:{ stmts; expr } 的值是最后一条语句的值。
486                    let span = self.current_pos();
487                    let block_stmt = self.block()?;
488                    Expr::new(ExprKind::Stmt(Box::new(block_stmt)), Span::new(span, self.current_pos()))
489                }
490            } else {
491                self.get_expr()?
492            };
493            self.whitespace()?;
494            let close = self.take(b';').is_ok();
495            let stmt = Stmt::new(StmtKind::Expr(value, close), Span::new(start, self.current_pos()));
496            Stmt::new(StmtKind::Let { pat, value: Box::new(stmt) }, Span::new(start, self.current_pos()))
497        } else if self.keyword("break").is_ok() {
498            self.until(b';')?;
499            Stmt::new(StmtKind::Break, Span::new(start, self.current_pos()))
500        } else if self.keyword("continue").is_ok() {
501            self.until(b';')?;
502            Stmt::new(StmtKind::Continue, Span::new(start, self.current_pos()))
503        } else if self.keyword("return").is_ok() {
504            self.whitespace()?;
505            let expr = if matches!(self.get(), Ok(b';' | b'}')) { None } else { Some(self.get_expr()?) };
506            self.whitespace()?;
507            if self.take(b';').is_err() && !matches!(self.get(), Ok(b'}')) {
508                self.until(b';')?;
509            }
510            Stmt::new(StmtKind::Return(expr), Span::new(start, self.current_pos()))
511        } else if self.keyword("if").is_ok() {
512            self.if_block()?
513        } else if self.keyword("loop").is_ok() {
514            Stmt::new(StmtKind::Loop(Box::new(self.block()?)), Span::new(start, self.current_pos()))
515        } else if self.keyword("while").is_ok() {
516            self.whitespace()?;
517            let cond = self.get_expr()?;
518            let body = Box::new(self.block()?);
519            Stmt::new(StmtKind::While { cond, body }, Span::new(start, self.current_pos()))
520        } else if self.keyword("for").is_ok() {
521            self.whitespace()?;
522            let pat = self.pattern()?;
523            self.whitespace()?;
524            self.keyword("in")?;
525            self.whitespace()?;
526            let range = self.get_expr()?;
527            self.push_decl_scope();
528            let result: Result<Stmt> = (|| {
529                self.declare_pattern_symbols(&pat)?;
530                let body = Box::new(self.block()?);
531                Ok(Stmt::new(StmtKind::For { pat, range, body }, Span::new(start, self.current_pos())))
532            })();
533            self.pop_decl_scope();
534            result?
535        } else if self.keyword("fn").is_ok() {
536            self.whitespace()?;
537            let (name, generic_params) = self.ident_generic()?;
538            self.declare_function_name(&name)?;
539            self.until(b'(')?;
540            let args = crate::parse_list!(self, Vec::new(), b')', b',', self.ident_typed()?);
541            let body = Box::new(self.function_body(&args)?);
542            Stmt::new(StmtKind::Fn { name, generic_params, args, body, is_pub }, Span::new(start, self.current_pos()))
543        } else if self.keyword("struct").is_ok() {
544            let (name, params) = self.ident_generic()?;
545            self.declare_symbol(&name)?;
546            if self.until(b'{').is_ok() {
547                let fields = crate::parse_list!(self, Vec::new(), b'}', b',', self.ident_typed()?);
548                if let Some(f) = fields.iter().find(|f| f.1.is_any()) {
549                    return Err(anyhow!("字段 {} 的类型未知", f.0));
550                }
551                Stmt::new(StmtKind::Struct { name, def: Type::Struct { params, fields }, is_pub }, Span::new(start, self.current_pos()))
552            } else {
553                self.until(b';')?;
554                Stmt::new(StmtKind::Struct { name, def: Type::Struct { params, fields: Vec::new() }, is_pub }, Span::new(start, self.current_pos()))
555            }
556        } else if self.keyword("const").is_ok() {
557            self.whitespace()?;
558            let (name, ty) = self.ident_typed()?;
559            self.declare_symbol(&name)?;
560            self.until(b'=')?;
561            let value = self.get_expr()?;
562            self.until(b';')?;
563            Stmt::new(StmtKind::Const { name, ty, value, is_pub }, Span::new(start, self.current_pos()))
564        } else if self.keyword("static").is_ok() {
565            self.whitespace()?;
566            let (name, ty) = self.ident_typed()?;
567            self.declare_symbol(&name)?;
568            self.whitespace()?;
569            if self.take(b'=').is_ok() {
570                let expr = self.get_expr()?;
571                self.until(b';')?;
572                Stmt::new(StmtKind::Static { name, ty, value: Some(expr), is_pub }, Span::new(start, self.current_pos()))
573            } else {
574                self.until(b';')?;
575                Stmt::new(StmtKind::Static { name, ty, value: None, is_pub }, Span::new(start, self.current_pos()))
576            }
577        } else if self.keyword("impl").is_ok() {
578            self.whitespace()?;
579            let target = self.get_type()?;
580            Stmt::new(StmtKind::Impl { target, body: Box::new(self.impl_body()?) }, Span::new(start, self.current_pos()))
581        } else if self.keyword("pub").is_ok() {
582            self.stmt(true)?
583        } else {
584            let expr = if self.get()? == b'{' {
585                if self.looks_like_empty_dict() {
586                    self.dict()?
587                } else if let Ok(block) = try_parse!(self, self.block()) {
588                    let _ = self.spans.pop();
589                    return Ok(block);
590                } else if let Ok(dict) = try_parse!(self, self.dict()) {
591                    dict
592                } else {
593                    let block = self.block()?;
594                    let _ = self.spans.pop();
595                    return Ok(block);
596                }
597            } else {
598                self.get_expr()?
599            };
600            self.whitespace()?;
601            if self.is_eof() {
602                Stmt::new(StmtKind::Expr(expr, false), Span::new(start, self.current_pos()))
603            } else if self.get()? == b';' {
604                self.pos += 1;
605                Stmt::new(StmtKind::Expr(expr, true), Span::new(start, self.current_pos()))
606            } else if self.get()? == b'}' {
607                Stmt::new(StmtKind::Expr(expr, false), Span::new(start, self.current_pos()))
608            } else {
609                return Err(anyhow!("未结束的表达式"));
610            }
611        };
612        let _ = self.spans.pop();
613        Ok(stmt)
614    }
615}
parser/stmt.rs

parser/
stmt.rs
