Phase 8.1 Complete: WASM backend foundation implementation

Co-authored-by: moe-charm <217100418+moe-charm@users.noreply.github.com>

src/backend/wasm/runtime.rs

@@ -0,0 +1,221 @@
+/*!
+ * WASM Runtime Imports - External function imports for WASM modules
+ * 
+ * Phase 8.2 PoC1: Implements env.print import for debugging
+ * Future: Additional runtime functions (file I/O, network, etc.)
+ */
+
+use super::WasmError;
+
+/// Runtime import definitions for WASM modules
+pub struct RuntimeImports {
+    /// Available imports
+    imports: Vec<ImportFunction>,
+}
+
+/// External function import definition
+#[derive(Debug, Clone)]
+pub struct ImportFunction {
+    pub module: String,
+    pub name: String,
+    pub params: Vec<String>,
+    pub result: Option<String>,
+}
+
+impl RuntimeImports {
+    pub fn new() -> Self {
+        let mut runtime = Self {
+            imports: Vec::new(),
+        };
+        
+        // Add standard runtime imports
+        runtime.add_standard_imports();
+        runtime
+    }
+    
+    /// Add standard runtime function imports
+    fn add_standard_imports(&mut self) {
+        // env.print for debugging output
+        self.imports.push(ImportFunction {
+            module: "env".to_string(),
+            name: "print".to_string(),
+            params: vec!["i32".to_string()],
+            result: None,
+        });
+        
+        // Future: env.print_string for string output
+        // Future: env.file_read, env.file_write for file I/O
+        // Future: env.http_request for network access
+    }
+    
+    /// Get all import declarations in WAT format
+    pub fn get_imports(&self) -> Vec<String> {
+        self.imports.iter().map(|import| {
+            let params = if import.params.is_empty() {
+                String::new()
+            } else {
+                format!("(param {})", import.params.join(" "))
+            };
+            
+            let result = if let Some(ref result_type) = import.result {
+                format!("(result {})", result_type)
+            } else {
+                String::new()
+            };
+            
+            format!(
+                "(import \"{}\" \"{}\" (func ${} {} {}))",
+                import.module,
+                import.name,
+                import.name,
+                params,
+                result
+            )
+        }).collect()
+    }
+    
+    /// Add custom import function
+    pub fn add_import(&mut self, module: String, name: String, params: Vec<String>, result: Option<String>) {
+        self.imports.push(ImportFunction {
+            module,
+            name,
+            params,
+            result,
+        });
+    }
+    
+    /// Check if an import is available
+    pub fn has_import(&self, name: &str) -> bool {
+        self.imports.iter().any(|import| import.name == name)
+    }
+    
+    /// Get import function by name
+    pub fn get_import(&self, name: &str) -> Option<&ImportFunction> {
+        self.imports.iter().find(|import| import.name == name)
+    }
+    
+    /// Generate JavaScript import object for browser execution
+    pub fn get_js_import_object(&self) -> String {
+        let mut js = String::new();
+        js.push_str("const importObject = {\n");
+        
+        // Group by module
+        let mut modules: std::collections::HashMap<String, Vec<&ImportFunction>> = std::collections::HashMap::new();
+        for import in &self.imports {
+            modules.entry(import.module.clone()).or_default().push(import);
+        }
+        
+        for (module_name, functions) in modules {
+            js.push_str(&format!("  {}: {{\n", module_name));
+            
+            for function in functions {
+                match function.name.as_str() {
+                    "print" => {
+                        js.push_str("    print: (value) => console.log(value),\n");
+                    },
+                    _ => {
+                        js.push_str(&format!("    {}: () => {{ throw new Error('Not implemented: {}'); }},\n", 
+                                           function.name, function.name));
+                    }
+                }
+            }
+            
+            js.push_str("  },\n");
+        }
+        
+        js.push_str("};\n");
+        js
+    }
+    
+    /// Generate Rust wasmtime import bindings
+    pub fn get_wasmtime_imports(&self) -> Result<String, WasmError> {
+        let mut rust_code = String::new();
+        rust_code.push_str("// Wasmtime import bindings\n");
+        rust_code.push_str("let mut imports = Vec::new();\n\n");
+        
+        for import in &self.imports {
+            match import.name.as_str() {
+                "print" => {
+                    rust_code.push_str(r#"
+let print_func = wasmtime::Func::wrap(&mut store, |value: i32| {
+    println!("{}", value);
+});
+imports.push(print_func.into());
+"#);
+                },
+                _ => {
+                    rust_code.push_str(&format!(r#"
+// TODO: Implement {} import
+let {}_func = wasmtime::Func::wrap(&mut store, || {{
+    panic!("Not implemented: {}")
+}});
+imports.push({}_func.into());
+"#, import.name, import.name, import.name, import.name));
+                }
+            }
+        }
+        
+        Ok(rust_code)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    
+    #[test]
+    fn test_runtime_imports_creation() {
+        let runtime = RuntimeImports::new();
+        assert!(!runtime.imports.is_empty());
+        assert!(runtime.has_import("print"));
+    }
+    
+    #[test]
+    fn test_import_wat_generation() {
+        let runtime = RuntimeImports::new();
+        let imports = runtime.get_imports();
+        
+        assert!(!imports.is_empty());
+        assert!(imports[0].contains("import"));
+        assert!(imports[0].contains("env"));
+        assert!(imports[0].contains("print"));
+    }
+    
+    #[test]
+    fn test_custom_import_addition() {
+        let mut runtime = RuntimeImports::new();
+        runtime.add_import(
+            "custom".to_string(),
+            "test_func".to_string(),
+            vec!["i32".to_string(), "i32".to_string()],
+            Some("i32".to_string())
+        );
+        
+        assert!(runtime.has_import("test_func"));
+        let import = runtime.get_import("test_func").unwrap();
+        assert_eq!(import.module, "custom");
+        assert_eq!(import.params.len(), 2);
+        assert!(import.result.is_some());
+    }
+    
+    #[test]
+    fn test_js_import_object_generation() {
+        let runtime = RuntimeImports::new();
+        let js = runtime.get_js_import_object();
+        
+        assert!(js.contains("importObject"));
+        assert!(js.contains("env"));
+        assert!(js.contains("print"));
+        assert!(js.contains("console.log"));
+    }
+    
+    #[test]
+    fn test_wasmtime_imports_generation() {
+        let runtime = RuntimeImports::new();
+        let rust_code = runtime.get_wasmtime_imports().unwrap();
+        
+        assert!(rust_code.contains("wasmtime::Func::wrap"));
+        assert!(rust_code.contains("print_func"));
+        assert!(rust_code.contains("println!"));
+    }
+}