harn_parser/
ast.rs

1use harn_lexer::{Span, StringSegment};
2
3/// A node wrapped with source location information.
4#[derive(Debug, Clone, PartialEq)]
5pub struct Spanned<T> {
6    pub node: T,
7    pub span: Span,
8}
9
10impl<T> Spanned<T> {
11    pub fn new(node: T, span: Span) -> Self {
12        Self { node, span }
13    }
14
15    pub fn dummy(node: T) -> Self {
16        Self {
17            node,
18            span: Span::dummy(),
19        }
20    }
21}
22
23/// A spanned AST node — the primary unit throughout the compiler.
24pub type SNode = Spanned<Node>;
25
26/// Helper to wrap a node with a span.
27pub fn spanned(node: Node, span: Span) -> SNode {
28    SNode::new(node, span)
29}
30
31/// AST nodes for the Harn language.
32#[derive(Debug, Clone, PartialEq)]
33pub enum Node {
34    // Declarations
35    Pipeline {
36        name: String,
37        params: Vec<String>,
38        body: Vec<SNode>,
39        extends: Option<String>,
40        is_pub: bool,
41    },
42    LetBinding {
43        pattern: BindingPattern,
44        type_ann: Option<TypeExpr>,
45        value: Box<SNode>,
46    },
47    VarBinding {
48        pattern: BindingPattern,
49        type_ann: Option<TypeExpr>,
50        value: Box<SNode>,
51    },
52    OverrideDecl {
53        name: String,
54        params: Vec<String>,
55        body: Vec<SNode>,
56    },
57    ImportDecl {
58        path: String,
59    },
60    /// Selective import: import { foo, bar } from "module"
61    SelectiveImport {
62        names: Vec<String>,
63        path: String,
64    },
65    EnumDecl {
66        name: String,
67        variants: Vec<EnumVariant>,
68        is_pub: bool,
69    },
70    StructDecl {
71        name: String,
72        fields: Vec<StructField>,
73        is_pub: bool,
74    },
75    InterfaceDecl {
76        name: String,
77        type_params: Vec<TypeParam>,
78        methods: Vec<InterfaceMethod>,
79    },
80    /// Impl block: impl TypeName { fn method(self, ...) { ... } ... }
81    ImplBlock {
82        type_name: String,
83        methods: Vec<SNode>,
84    },
85
86    // Control flow
87    IfElse {
88        condition: Box<SNode>,
89        then_body: Vec<SNode>,
90        else_body: Option<Vec<SNode>>,
91    },
92    ForIn {
93        pattern: BindingPattern,
94        iterable: Box<SNode>,
95        body: Vec<SNode>,
96    },
97    MatchExpr {
98        value: Box<SNode>,
99        arms: Vec<MatchArm>,
100    },
101    WhileLoop {
102        condition: Box<SNode>,
103        body: Vec<SNode>,
104    },
105    Retry {
106        count: Box<SNode>,
107        body: Vec<SNode>,
108    },
109    ReturnStmt {
110        value: Option<Box<SNode>>,
111    },
112    TryCatch {
113        body: Vec<SNode>,
114        error_var: Option<String>,
115        error_type: Option<TypeExpr>,
116        catch_body: Vec<SNode>,
117        finally_body: Option<Vec<SNode>>,
118    },
119    /// Try expression: try { body } — returns Result.Ok(value) or Result.Err(error).
120    TryExpr {
121        body: Vec<SNode>,
122    },
123    FnDecl {
124        name: String,
125        type_params: Vec<TypeParam>,
126        params: Vec<TypedParam>,
127        return_type: Option<TypeExpr>,
128        where_clauses: Vec<WhereClause>,
129        body: Vec<SNode>,
130        is_pub: bool,
131    },
132    ToolDecl {
133        name: String,
134        description: Option<String>,
135        params: Vec<TypedParam>,
136        return_type: Option<TypeExpr>,
137        body: Vec<SNode>,
138        is_pub: bool,
139    },
140    TypeDecl {
141        name: String,
142        type_expr: TypeExpr,
143    },
144    SpawnExpr {
145        body: Vec<SNode>,
146    },
147    /// Duration literal: 500ms, 5s, 30m, 2h, 1d, 1w
148    DurationLiteral(u64),
149    /// Range expression: start upto end (exclusive) or start thru end (inclusive)
150    RangeExpr {
151        start: Box<SNode>,
152        end: Box<SNode>,
153        inclusive: bool,
154    },
155    /// Guard clause: guard condition else { body }
156    GuardStmt {
157        condition: Box<SNode>,
158        else_body: Vec<SNode>,
159    },
160    RequireStmt {
161        condition: Box<SNode>,
162        message: Option<Box<SNode>>,
163    },
164    /// Defer statement: defer { body } — runs body at scope exit.
165    DeferStmt {
166        body: Vec<SNode>,
167    },
168    /// Deadline block: deadline DURATION { body }
169    DeadlineBlock {
170        duration: Box<SNode>,
171        body: Vec<SNode>,
172    },
173    /// Yield expression: yields control to host, optionally with a value.
174    YieldExpr {
175        value: Option<Box<SNode>>,
176    },
177    /// Mutex block: mutual exclusion for concurrent access.
178    MutexBlock {
179        body: Vec<SNode>,
180    },
181    /// Break out of a loop.
182    BreakStmt,
183    /// Continue to next loop iteration.
184    ContinueStmt,
185
186    // Concurrency
187    Parallel {
188        mode: ParallelMode,
189        /// For Count mode: the count expression. For Each/Settle: the list expression.
190        expr: Box<SNode>,
191        variable: Option<String>,
192        body: Vec<SNode>,
193    },
194
195    SelectExpr {
196        cases: Vec<SelectCase>,
197        timeout: Option<(Box<SNode>, Vec<SNode>)>,
198        default_body: Option<Vec<SNode>>,
199    },
200
201    // Expressions
202    FunctionCall {
203        name: String,
204        args: Vec<SNode>,
205    },
206    MethodCall {
207        object: Box<SNode>,
208        method: String,
209        args: Vec<SNode>,
210    },
211    /// Optional method call: `obj?.method(args)` — returns nil if obj is nil.
212    OptionalMethodCall {
213        object: Box<SNode>,
214        method: String,
215        args: Vec<SNode>,
216    },
217    PropertyAccess {
218        object: Box<SNode>,
219        property: String,
220    },
221    /// Optional chaining: `obj?.property` — returns nil if obj is nil.
222    OptionalPropertyAccess {
223        object: Box<SNode>,
224        property: String,
225    },
226    SubscriptAccess {
227        object: Box<SNode>,
228        index: Box<SNode>,
229    },
230    SliceAccess {
231        object: Box<SNode>,
232        start: Option<Box<SNode>>,
233        end: Option<Box<SNode>>,
234    },
235    BinaryOp {
236        op: String,
237        left: Box<SNode>,
238        right: Box<SNode>,
239    },
240    UnaryOp {
241        op: String,
242        operand: Box<SNode>,
243    },
244    Ternary {
245        condition: Box<SNode>,
246        true_expr: Box<SNode>,
247        false_expr: Box<SNode>,
248    },
249    Assignment {
250        target: Box<SNode>,
251        value: Box<SNode>,
252        /// None = plain `=`, Some("+") = `+=`, etc.
253        op: Option<String>,
254    },
255    ThrowStmt {
256        value: Box<SNode>,
257    },
258
259    /// Enum variant construction: EnumName.Variant(args)
260    EnumConstruct {
261        enum_name: String,
262        variant: String,
263        args: Vec<SNode>,
264    },
265    /// Struct construction: StructName { field: value, ... }
266    StructConstruct {
267        struct_name: String,
268        fields: Vec<DictEntry>,
269    },
270
271    // Literals
272    InterpolatedString(Vec<StringSegment>),
273    StringLiteral(String),
274    /// Raw string literal `r"..."` — no escape processing.
275    RawStringLiteral(String),
276    IntLiteral(i64),
277    FloatLiteral(f64),
278    BoolLiteral(bool),
279    NilLiteral,
280    Identifier(String),
281    ListLiteral(Vec<SNode>),
282    DictLiteral(Vec<DictEntry>),
283    /// Spread expression `...expr` inside list/dict literals.
284    Spread(Box<SNode>),
285    /// Try operator: expr? — unwraps Result.Ok or propagates Result.Err.
286    TryOperator {
287        operand: Box<SNode>,
288    },
289
290    // Blocks
291    Block(Vec<SNode>),
292    Closure {
293        params: Vec<TypedParam>,
294        body: Vec<SNode>,
295        /// When true, this closure was written as `fn(params) { body }`.
296        /// The formatter preserves this distinction.
297        fn_syntax: bool,
298    },
299}
300
301/// Parallel execution mode.
302#[derive(Debug, Clone, Copy, PartialEq)]
303pub enum ParallelMode {
304    /// `parallel N { i -> ... }` — run N concurrent tasks.
305    Count,
306    /// `parallel each list { item -> ... }` — map over list concurrently.
307    Each,
308    /// `parallel settle list { item -> ... }` — map with error collection.
309    Settle,
310}
311
312#[derive(Debug, Clone, PartialEq)]
313pub struct MatchArm {
314    pub pattern: SNode,
315    /// Optional guard: `pattern if condition -> { body }`.
316    pub guard: Option<Box<SNode>>,
317    pub body: Vec<SNode>,
318}
319
320#[derive(Debug, Clone, PartialEq)]
321pub struct SelectCase {
322    pub variable: String,
323    pub channel: Box<SNode>,
324    pub body: Vec<SNode>,
325}
326
327#[derive(Debug, Clone, PartialEq)]
328pub struct DictEntry {
329    pub key: SNode,
330    pub value: SNode,
331}
332
333/// An enum variant declaration.
334#[derive(Debug, Clone, PartialEq)]
335pub struct EnumVariant {
336    pub name: String,
337    pub fields: Vec<TypedParam>,
338}
339
340/// A struct field declaration.
341#[derive(Debug, Clone, PartialEq)]
342pub struct StructField {
343    pub name: String,
344    pub type_expr: Option<TypeExpr>,
345    pub optional: bool,
346}
347
348/// An interface method signature.
349#[derive(Debug, Clone, PartialEq)]
350pub struct InterfaceMethod {
351    pub name: String,
352    pub type_params: Vec<TypeParam>,
353    pub params: Vec<TypedParam>,
354    pub return_type: Option<TypeExpr>,
355}
356
357/// A type annotation (optional, for runtime checking).
358#[derive(Debug, Clone, PartialEq)]
359pub enum TypeExpr {
360    /// A named type: int, string, float, bool, nil, list, dict, closure,
361    /// or a user-defined type name.
362    Named(String),
363    /// A union type: `string | nil`, `int | float`.
364    Union(Vec<TypeExpr>),
365    /// A dict shape type: `{name: string, age: int, active?: bool}`.
366    Shape(Vec<ShapeField>),
367    /// A list type: `list<int>`.
368    List(Box<TypeExpr>),
369    /// A dict type with key and value types: `dict<string, int>`.
370    DictType(Box<TypeExpr>, Box<TypeExpr>),
371    /// A function type: `fn(int, string) -> bool`.
372    FnType {
373        params: Vec<TypeExpr>,
374        return_type: Box<TypeExpr>,
375    },
376    /// The bottom type: the type of expressions that never produce a value
377    /// (return, throw, break, continue).
378    Never,
379}
380
381/// A field in a dict shape type.
382#[derive(Debug, Clone, PartialEq)]
383pub struct ShapeField {
384    pub name: String,
385    pub type_expr: TypeExpr,
386    pub optional: bool,
387}
388
389/// A binding pattern for destructuring in let/var/for-in.
390#[derive(Debug, Clone, PartialEq)]
391pub enum BindingPattern {
392    /// Simple identifier: `let x = ...`
393    Identifier(String),
394    /// Dict destructuring: `let {name, age} = ...`
395    Dict(Vec<DictPatternField>),
396    /// List destructuring: `let [a, b] = ...`
397    List(Vec<ListPatternElement>),
398}
399
400/// A field in a dict destructuring pattern.
401#[derive(Debug, Clone, PartialEq)]
402pub struct DictPatternField {
403    /// The dict key to extract.
404    pub key: String,
405    /// Renamed binding (if different from key), e.g. `{name: alias}`.
406    pub alias: Option<String>,
407    /// True for `...rest` (rest pattern).
408    pub is_rest: bool,
409    /// Default value if the key is missing (nil), e.g. `{name = "default"}`.
410    pub default_value: Option<Box<SNode>>,
411}
412
413/// An element in a list destructuring pattern.
414#[derive(Debug, Clone, PartialEq)]
415pub struct ListPatternElement {
416    /// The variable name to bind.
417    pub name: String,
418    /// True for `...rest` (rest pattern).
419    pub is_rest: bool,
420    /// Default value if the index is out of bounds (nil), e.g. `[a = 0]`.
421    pub default_value: Option<Box<SNode>>,
422}
423
424/// A generic type parameter on a function or pipeline declaration.
425#[derive(Debug, Clone, PartialEq)]
426pub struct TypeParam {
427    pub name: String,
428}
429
430/// A where-clause constraint on a generic type parameter.
431#[derive(Debug, Clone, PartialEq)]
432pub struct WhereClause {
433    pub type_name: String,
434    pub bound: String,
435}
436
437/// A parameter with an optional type annotation and optional default value.
438#[derive(Debug, Clone, PartialEq)]
439pub struct TypedParam {
440    pub name: String,
441    pub type_expr: Option<TypeExpr>,
442    pub default_value: Option<Box<SNode>>,
443    /// If true, this is a rest parameter (`...name`) that collects remaining arguments.
444    pub rest: bool,
445}
446
447impl TypedParam {
448    /// Create an untyped parameter.
449    pub fn untyped(name: impl Into<String>) -> Self {
450        Self {
451            name: name.into(),
452            type_expr: None,
453            default_value: None,
454            rest: false,
455        }
456    }
457
458    /// Create a typed parameter.
459    pub fn typed(name: impl Into<String>, type_expr: TypeExpr) -> Self {
460        Self {
461            name: name.into(),
462            type_expr: Some(type_expr),
463            default_value: None,
464            rest: false,
465        }
466    }
467
468    /// Extract just the names from a list of typed params.
469    pub fn names(params: &[TypedParam]) -> Vec<String> {
470        params.iter().map(|p| p.name.clone()).collect()
471    }
472
473    /// Return the index of the first parameter with a default value, or None.
474    pub fn default_start(params: &[TypedParam]) -> Option<usize> {
475        params.iter().position(|p| p.default_value.is_some())
476    }
477}
harn_parser/ast.rs

harn_parser/
ast.rs
