cairo_lang_plugins/plugins/
panicable.rs

1use cairo_lang_defs::patcher::{PatchBuilder, RewriteNode};
2use cairo_lang_defs::plugin::{
3    MacroPlugin, MacroPluginMetadata, PluginDiagnostic, PluginGeneratedFile, PluginResult,
4};
5use cairo_lang_filesystem::ids::SmolStrId;
6use cairo_lang_syntax::attribute::structured::{
7    Attribute, AttributeArg, AttributeArgVariant, AttributeStructurize,
8};
9use cairo_lang_syntax::node::helpers::{GetIdentifier, QueryAttrs};
10use cairo_lang_syntax::node::{TypedSyntaxNode, ast};
11use cairo_lang_utils::try_extract_matches;
12use indoc::formatdoc;
13use itertools::Itertools;
14use salsa::Database;
15
16#[derive(Debug, Default)]
17#[non_exhaustive]
18pub struct PanicablePlugin;
19
20const PANIC_WITH_ATTR: &str = "panic_with";
21
22impl MacroPlugin for PanicablePlugin {
23    fn generate_code<'db>(
24        &self,
25        db: &'db dyn Database,
26        item_ast: ast::ModuleItem<'db>,
27        _metadata: &MacroPluginMetadata<'_>,
28    ) -> PluginResult<'db> {
29        let (declaration, attributes, visibility) = match item_ast {
30            ast::ModuleItem::ExternFunction(extern_func_ast) => (
31                extern_func_ast.declaration(db),
32                extern_func_ast.attributes(db),
33                extern_func_ast.visibility(db),
34            ),
35            ast::ModuleItem::FreeFunction(free_func_ast) => (
36                free_func_ast.declaration(db),
37                free_func_ast.attributes(db),
38                free_func_ast.visibility(db),
39            ),
40            _ => return PluginResult::default(),
41        };
42
43        generate_panicable_code(db, declaration, attributes, visibility)
44    }
45
46    fn declared_attributes<'db>(&self, db: &'db dyn Database) -> Vec<SmolStrId<'db>> {
47        vec![SmolStrId::from(db, PANIC_WITH_ATTR)]
48    }
49}
50
51/// Generate code defining a panicable variant of a function marked with `#[panic_with]` attribute.
52fn generate_panicable_code<'db>(
53    db: &'db dyn Database,
54    declaration: ast::FunctionDeclaration<'db>,
55    attributes: ast::AttributeList<'db>,
56    visibility: ast::Visibility<'db>,
57) -> PluginResult<'db> {
58    let mut attrs = attributes.query_attr(db, PANIC_WITH_ATTR);
59    let Some(attr) = attrs.next() else {
60        // No `#[panic_with]` attribute found.
61        return PluginResult::default();
62    };
63    let mut diagnostics = vec![];
64    if let Some(extra_attr) = attrs.next() {
65        diagnostics.push(PluginDiagnostic::error(
66            extra_attr.stable_ptr(db),
67            "`#[panic_with]` cannot be applied multiple times to the same item.".into(),
68        ));
69        return PluginResult { code: None, diagnostics, remove_original_item: false };
70    }
71
72    let signature = declaration.signature(db);
73    let Some((inner_ty, success_variant, failure_variant)) =
74        extract_success_ty_and_variants(db, &signature)
75    else {
76        diagnostics.push(PluginDiagnostic::error(
77            signature.ret_ty(db).stable_ptr(db),
78            "Currently only wrapping functions returning an Option<T> or Result<T, E>".into(),
79        ));
80        return PluginResult { code: None, diagnostics, remove_original_item: false };
81    };
82
83    let mut builder = PatchBuilder::new(db, &attr);
84    let attr = attr.structurize(db);
85
86    let Some((err_value, panicable_name)) = parse_arguments(db, &attr) else {
87        diagnostics.push(PluginDiagnostic::error(
88            attr.stable_ptr,
89            "Failed to extract panic data attribute".into(),
90        ));
91        return PluginResult { code: None, diagnostics, remove_original_item: false };
92    };
93    builder.add_node(visibility.as_syntax_node());
94    builder.add_node(declaration.function_kw(db).as_syntax_node());
95    builder.add_modified(RewriteNode::from_ast_trimmed(&panicable_name));
96    builder.add_node(declaration.generic_params(db).as_syntax_node());
97    builder.add_node(signature.lparen(db).as_syntax_node());
98    builder.add_node(signature.parameters(db).as_syntax_node());
99    builder.add_node(signature.rparen(db).as_syntax_node());
100    let args = signature
101        .parameters(db)
102        .elements(db)
103        .map(|param| {
104            let ref_kw =
105                if let Ok(ast::Modifier::Ref(_)) = param.modifiers(db).elements(db).exactly_one() {
106                    "ref "
107                } else {
108                    ""
109                };
110            format!("{}{}", ref_kw, param.name(db).as_syntax_node().get_text(db))
111        })
112        .join(", ");
113    builder.add_modified(RewriteNode::interpolate_patched(
114        &formatdoc!(
115            r#"
116                -> $inner_ty$ {{
117                    match $function_name$({args}) {{
118                        {success_variant}(v) => v,
119                        {failure_variant}(_) => core::panic_with_const_felt252::<$err_value$>(),
120                    }}
121                }}
122            "#
123        ),
124        &[
125            ("inner_ty".to_string(), RewriteNode::from_ast_trimmed(&inner_ty)),
126            ("function_name".to_string(), RewriteNode::from_ast_trimmed(&declaration.name(db))),
127            ("err_value".to_string(), RewriteNode::from_ast_trimmed(&err_value)),
128        ]
129        .into(),
130    ));
131
132    let (content, code_mappings) = builder.build();
133    PluginResult {
134        code: Some(PluginGeneratedFile {
135            name: "panicable".into(),
136            content,
137            code_mappings,
138            aux_data: None,
139            diagnostics_note: Default::default(),
140            is_unhygienic: false,
141        }),
142        diagnostics,
143        remove_original_item: false,
144    }
145}
146
147/// Given a function signature, if it returns `Option::<T>` or `Result::<T, E>`, returns T and the
148/// variant match strings. Otherwise, returns None.
149fn extract_success_ty_and_variants<'a>(
150    db: &'a dyn Database,
151    signature: &ast::FunctionSignature<'a>,
152) -> Option<(ast::GenericArg<'a>, String, String)> {
153    let ret_ty_expr =
154        try_extract_matches!(signature.ret_ty(db), ast::OptionReturnTypeClause::ReturnTypeClause)?
155            .ty(db);
156    let ret_ty_path = try_extract_matches!(ret_ty_expr, ast::Expr::Path)?;
157
158    // Currently wrapping functions returning an Option<T> or Result<T, E>.
159    let Ok(ast::PathSegment::WithGenericArgs(segment)) =
160        ret_ty_path.segments(db).elements(db).exactly_one()
161    else {
162        return None;
163    };
164    let ty = segment.identifier(db).long(db);
165    if ty == "Option" {
166        let inner = segment.generic_args(db).generic_args(db).elements(db).exactly_one().ok()?;
167        Some((inner.clone(), "Option::Some".to_owned(), "Option::None".to_owned()))
168    } else if ty == "Result" {
169        let [inner, _err] =
170            segment.generic_args(db).generic_args(db).elements(db).collect_array()?;
171        Some((inner.clone(), "Result::Ok".to_owned(), "Result::Err".to_owned()))
172    } else {
173        None
174    }
175}
176
177/// Parse `#[panic_with(...)]` attribute arguments and return a tuple with error value and
178/// panicable function name.
179fn parse_arguments<'a>(
180    db: &'a dyn Database,
181    attr: &Attribute<'a>,
182) -> Option<(ast::TerminalShortString<'a>, ast::TerminalIdentifier<'a>)> {
183    let [
184        AttributeArg {
185            variant: AttributeArgVariant::Unnamed(ast::Expr::ShortString(err_value)),
186            ..
187        },
188        AttributeArg { variant: AttributeArgVariant::Unnamed(ast::Expr::Path(name)), .. },
189    ] = &attr.args[..]
190    else {
191        return None;
192    };
193
194    let Ok(ast::PathSegment::Simple(segment)) = name.segments(db).elements(db).exactly_one() else {
195        return None;
196    };
197
198    Some((err_value.clone(), segment.ident(db)))
199}
cairo_lang_plugins/plugins/panicable.rs

cairo_lang_plugins/plugins/
panicable.rs
