alef 0.24.17

Opinionated polyglot binding generator for Rust libraries
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227

use crate::codegen::naming::to_node_name;
use crate::core::backend::GeneratedFile;
use crate::core::config::{NodeCapsuleTypeConfig, ResolvedCrateConfig, TraitBridgeConfig};
use crate::core::ir::ApiSurface;
use std::collections::HashMap;
use std::path::PathBuf;

pub(super) fn generate(api: &ApiSurface, config: &ResolvedCrateConfig) -> anyhow::Result<Vec<GeneratedFile>> {
    // Collect all exported names from the native module.
    // These are used to construct named re-exports that work with both CJS and ESM.
    let mut value_names = std::collections::BTreeSet::new();
    let mut type_names = std::collections::BTreeSet::new();

    // Collect struct and class types (skip traits and capsule types)
    let capsule_types: HashMap<String, NodeCapsuleTypeConfig> = config
        .node
        .as_ref()
        .map(|c| c.capsule_types.clone())
        .unwrap_or_default();
    for typ in api.types.iter() {
        // The napi binding filters out Builder/Update DTOs (see the
        // filters at lines 382/643/735/776) — exclude them here too so
        // the typescript wrapper does not re-export names that the
        // native module never emits.
        if !typ.is_trait
            && !capsule_types.contains_key(&typ.name)
            && !typ.name.ends_with("Builder")
            && !typ.name.ends_with("Update")
        {
            if typ.is_opaque {
                value_names.insert(typ.name.clone());
            } else {
                type_names.insert(typ.name.clone());
            }
        }
    }

    // Collect enums
    for enum_def in &api.enums {
        if enum_def.variants.iter().any(|v| !v.fields.is_empty()) {
            type_names.insert(enum_def.name.clone());
        } else {
            value_names.insert(enum_def.name.clone());
        }
    }

    // Runtime classes/enums can also be used as types. Keep type-only
    // exports disjoint from value exports so the wrapper barrel never emits
    // the same name in both export groups.
    for name in &value_names {
        type_names.remove(name);
    }

    // Collect functions (with snake_case → camelCase conversion for JS naming)
    let exclude_functions: ahash::AHashSet<String> = config
        .node
        .as_ref()
        .map(|c| c.exclude_functions.iter().cloned().collect())
        .unwrap_or_default();
    for func in &api.functions {
        if !exclude_functions.contains(&func.name) {
            value_names.insert(to_node_name(&func.name));
        }
    }

    // Include trait-bridge register/unregister/clear functions
    for bridge in &config.trait_bridges {
        if let Some(name) = bridge.register_fn.as_deref() {
            value_names.insert(to_node_name(name));
        }
        if let Some(name) = bridge.unregister_fn.as_deref() {
            value_names.insert(to_node_name(name));
        }
        if let Some(name) = bridge.clear_fn.as_deref() {
            value_names.insert(to_node_name(name));
        }
    }

    // Generate TypeScript re-export file using explicit named re-exports.
    // This works with both CJS and ESM because we use `export { name } from "module"`
    // which TypeScript understands regardless of the underlying CJS/ESM implementation.
    let package_name = config.node_package_name();
    let mut lines = vec![];

    // Export runtime values (functions, classes, enums) as regular exports.
    if !value_names.is_empty() {
        lines.push("export {".to_string());
        for name in &value_names {
            lines.push(format!("  {name},"));
        }
        lines.push(format!("}} from \"{}\";", package_name));
        lines.push("".to_string());
    }

    // Export types as type-only exports (TypeScript 4.5+)
    if !type_names.is_empty() {
        lines.push("export type {".to_string());
        for name in &type_names {
            lines.push(format!("  {name},"));
        }
        lines.push(format!("}} from \"{}\";", package_name));
        lines.push("".to_string());
    }

    // Note: custom_modules (if any) are not included in this wrapper because:
    // 1. packages/typescript/src/ is the wrapper package, which only re-exports from the native binding
    // 2. custom modules (e.g., helpers) are shipped in dist/ by the build system, not generated by alef
    // 3. including them here would require them to exist in src/, which they don't

    let content = lines.join("\n");

    // Output path: packages/typescript/src/index.ts
    let output_path = PathBuf::from("packages/typescript/src/index.ts");

    let mut files = vec![GeneratedFile {
        path: output_path,
        content,
        generated_header: true,
    }];

    // Generate TypeScript trait bridge files (interfaces and adapters)
    let bridges: Vec<(String, &TraitBridgeConfig, &crate::core::ir::TypeDef)> = config
        .trait_bridges
        .iter()
        .filter_map(|bridge_cfg| {
            api.types
                .iter()
                .find(|t| t.is_trait && t.name == bridge_cfg.trait_name)
                .map(|trait_def| (bridge_cfg.trait_name.clone(), bridge_cfg, trait_def))
        })
        .collect();

    for (trait_name, _bridge_cfg, trait_def) in &bridges {
        let ts_file_content = gen_single_typescript_trait_bridge(trait_name, trait_def);
        let ts_file_path = PathBuf::from(format!("packages/typescript/src/bridges/{}Bridge.ts", trait_name));
        files.push(GeneratedFile {
            path: ts_file_path,
            content: ts_file_content,
            generated_header: true,
        });
    }

    Ok(files)
}

/// Generate a single TypeScript trait bridge file with interface and adapter class.
fn gen_single_typescript_trait_bridge(trait_name: &str, trait_def: &crate::core::ir::TypeDef) -> String {
    use heck::ToLowerCamelCase;

    let bridge_interface_name = format!("{}Bridge", trait_name);
    let adapter_class_name = format!("{}Adapter", trait_name);

    let mut interface_methods = String::new();
    let mut adapter_methods = String::new();

    for method in &trait_def.methods {
        let method_camel = method.name.to_lower_camel_case();
        let has_error = method.error_type.is_some();

        // Generate parameter list
        let params = method
            .params
            .iter()
            .map(|p| {
                let param_name = p.name.to_lower_camel_case();
                format!("{}: string", param_name) // All params marshalled as JSON strings at boundary
            })
            .collect::<Vec<_>>()
            .join(", ");

        // Generate return type (all returns are strings for JSON marshalling)
        let return_type = "string";
        let optional_mark = if has_error { "?" } else { "" };

        // Interface method - make it optional if it can throw (error_type.is_some())
        interface_methods.push_str(&format!(
            "  {}{}({}): {};\n",
            method_camel, optional_mark, params, return_type
        ));

        // Adapter method delegate
        let call_args = method
            .params
            .iter()
            .map(|p| p.name.to_lower_camel_case())
            .collect::<Vec<_>>()
            .join(", ");

        adapter_methods.push_str(&format!(
            "  async {}({}): Promise<{}> {{\n",
            method_camel, params, return_type
        ));
        adapter_methods.push_str(&format!(
            "    try {{\n      const result = await this.bridge.{}({});\n",
            method_camel, call_args
        ));
        adapter_methods.push_str("      return JSON.stringify({ ok: result });\n");
        adapter_methods.push_str("    } catch (e) {\n");
        adapter_methods.push_str("      return JSON.stringify({ err: String(e) });\n");
        adapter_methods.push_str("    }\n");
        adapter_methods.push_str("  }\n\n");
    }

    // Generate full file content
    let mut content = String::new();
    content.push_str("/**\n");
    content.push_str(" * Generated by alef. Do not edit by hand.\n");
    content.push_str(" * \n");
    content.push_str(" * TypeScript trait bridge for outbound plugin implementations.\n");
    content.push_str(" */\n\n");

    // Interface
    content.push_str(&format!(
        "export interface {} {{\n  name(): string;\n  version(): string;\n  initialize(): Promise<void>;\n  shutdown(): Promise<void>;\n{}}}",
        bridge_interface_name, interface_methods
    ));

    content.push_str("\n\n");

    // Adapter class
    content.push_str(&format!(
        "export class {} {{\n  constructor(private bridge: {}) {{}}\n\n{}}}",
        adapter_class_name, bridge_interface_name, adapter_methods
    ));

    content
}