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

harn_parser/
ast.rs
