1 files changed, 124 insertions, 0 deletions
diff --git a/src/bind/AutoBinder.kt b/src/bind/AutoBinder.kt
new file mode 100644
index 0000000..83d5d86
--- /dev/null
+++ b/src/bind/AutoBinder.kt
@@ -0,0 +1,124 @@
+package moe.nea.lisp.bind
+
+import moe.nea.lisp.*
+import java.lang.invoke.MethodHandles
+import java.lang.reflect.Method
+import java.lang.reflect.Modifier
+import java.lang.reflect.Parameter
+
+class AutoBinder {
+
+    private fun mapLispData(parameter: Parameter): ((Iterator<LispData>, ErrorReporter) -> Any)? {
+        if (LispData::class.java.isAssignableFrom(parameter.type)) return { a, b -> parameter.type.cast(a.next()) }
+        return null
+    }
+
+    private fun mapErrorReporter(parameter: Parameter): ((Iterator<LispData>, ErrorReporter) -> Any)? {
+        if (ErrorReporter::class.java.isAssignableFrom(parameter.type)) return { a, b -> b }
+        return null
+    }
+
+    private fun mapString(parameter: Parameter): ((Iterator<LispData>, ErrorReporter) -> Any?)? {
+        if (String::class.java == parameter.type) return { a, b ->
+            when (val x = a.next()) {
+                is LispData.LispString -> x.string
+                is LispData.Atom -> x.label
+                else -> null.also { b.reportError("Could not coerce $x to string") }
+            }
+        }
+        return null
+    }
+
+    private fun mapBoolean(parameter: Parameter): ((Iterator<LispData>, ErrorReporter) -> Any?)? {
+        if (Boolean::class.java.isAssignableFrom(parameter.type)) return { a, b ->
+            val x = a.next()
+            val y = CoreBindings.isTruthy(x)
+            if (y == null) {
+                b.reportError("Could not coerce $x to a boolean")
+            }
+            y
+        }
+        return null
+    }
+
+    private fun mapNumber(parameter: Parameter): ((Iterator<LispData>, ErrorReporter) -> Any?)? {
+        if (Double::class.java.isAssignableFrom(parameter.type)) return { a, b ->
+            when (val x = a.next()) {
+                is LispData.LispNumber -> x.value
+                else -> null.also { b.reportError("Could not coerce $x to number") }
+            }
+        }
+        if (Float::class.java.isAssignableFrom(parameter.type)) return { a, b ->
+            when (val x = a.next()) {
+                is LispData.LispNumber -> x.value.toFloat()
+                else -> null.also { b.reportError("Could not coerce $x to number") }
+            }
+        }
+        if (Int::class.java.isAssignableFrom(parameter.type)) return { a, b ->
+            when (val x = a.next()) {
+                is LispData.LispNumber -> x.value.toInt()
+                else -> null.also { b.reportError("Could not coerce $x to number") }
+            }
+        }
+        if (Long::class.java.isAssignableFrom(parameter.type)) return { a, b ->
+            when (val x = a.next()) {
+                is LispData.LispNumber -> x.value.toLong()
+                else -> null.also { b.reportError("Could not coerce $x to number") }
+            }
+        }
+        return null
+    }
+
+
+    val objectMappers = mutableListOf<((Parameter) -> (((Iterator<LispData>, ErrorReporter) -> Any?)?))>(
+        ::mapLispData,
+        ::mapErrorReporter,
+        ::mapNumber,
+        ::mapString,
+        ::mapBoolean,
+    )
+
+
+    fun generateInstanceBindings(obj: Any): Map<String, LispData> {
+        val bindings = mutableMapOf<String, LispData>()
+        for (method in obj.javaClass.methods) {
+            val annotation = method.getAnnotation(LispBinding::class.java)
+            if (annotation == null) continue
+            require(LispParser.isValidIdentifier(annotation.name))
+            bindings[annotation.name] = wrapMethod(obj, annotation.name, method)
+        }
+        // TODO: field bindings
+        return bindings
+    }
+
+    private val lookup = MethodHandles.publicLookup()
+    fun wrapMethod(obj: Any, name: String, method: Method): LispData.LispExecutable {
+        var mh = lookup.unreflect(method)
+        if (method.modifiers and Modifier.STATIC == 0) {
+            mh = mh.bindTo(obj)
+        }
+        val objectMappers = method.parameters.map { param ->
+            objectMappers.firstNotNullOfOrNull { it.invoke(param) }
+                ?: error("Could not find object mapper for parameter $param")
+        }
+        return LispData.externalCall(name) { args, fReportError ->
+            try {
+                val iterator = args.iterator()
+                val e = object : ErrorReporter {
+                    override fun reportError(string: String): LispData {
+                        return fReportError(string)
+                    }
+                }
+                val p = objectMappers.map { it.invoke(iterator, e) ?: return@externalCall LispData.LispNil }
+                if (iterator.hasNext()) return@externalCall fReportError("Too many arguments")
+                mh.invokeWithArguments(p) as LispData
+            } catch (e: Exception) {
+                fReportError("$name threw an exception: $e")
+            }
+        }
+    }
+
+    fun bindTo(obj: Any, frame: StackFrame) {
+        frame.variables.putAll(generateInstanceBindings(obj))
+    }
+}
+\ No newline at end of file