Handle errors

Author: jerrymarino

Sources/Vim/Vim.swift

@@ -1,34 +1,51 @@
 import VimInterface
 
+enum VimError: Error {
+    case invalidCall(String)
+}
+
 public struct Vim {
     public static var current: Current {
         return Current()
     }
 
     /// Run a vim command
-    @discardableResult public static func command(_ cmd: String) -> VimValue? {
+    @discardableResult public static func command(_ cmd: String) throws -> VimValue  {
         var value: VimValue?
         cmd.withCString { cStr in
-            //FIXME: handle error propagation
             if let result = swiftvim_command(
                 UnsafeMutablePointer(mutating: cStr)) {
                 value = VimValue(result)
             }
         }
-        return value
+        if let value = value {
+            return value
+        }
+        throw getCallError(context: cmd)
     }
 
     /// Evaluate an expression
-    @discardableResult public static func eval(_ cmd: String) -> VimValue? {
+    @discardableResult public static func eval(_ cmd: String) throws -> VimValue {
         var value: VimValue?
         cmd.withCString { cStr in
-            //FIXME: handle error propagation
             if let result = swiftvim_eval(
                 UnsafeMutablePointer(mutating: cStr)) {
                 value = VimValue(result)
             }
         }
-        return value
+        if let value = value {
+            return value
+        }
+        throw getCallError(context: cmd)
+    }
+
+    private static func getCallError(context: String) -> VimError {
+        if let error = swiftvim_get_error() {
+            if let base = swiftvim_asstring(error) {
+                return VimError.invalidCall(String(cString: base) + " - " + context)
+            }
+        }
+        return VimError.invalidCall(context)
     }
 }
 

Sources/VimInterface/include/VimInterface/swiftvim.h

@@ -47,3 +47,6 @@ void *_Nullable swiftvim_call_impl(void *_Nonnull func, void *_Nullable arg1, vo
 void swiftvim_initialize();
 void swiftvim_finalize();
 
+void *_Nullable swiftvim_get_error();
+
+

Sources/VimInterface/swiftvim_lib.c

@@ -319,3 +319,17 @@ VIM_INTEN void swiftvim_finalize() {
     Py_Finalize();
 }
 
+
+VIM_INTEN void *_Nullable swiftvim_get_error() {
+    if (PyErr_Occurred()) {
+        PyObject *type, *value, *traceback;
+        PyErr_Fetch(&type, &value, &traceback);
+        if (value) {
+            return value;
+        } else {
+            return type;
+        }
+    }
+    return NULL;
+}
+

Sources/VimKit/VimExtensions.swift

@@ -29,27 +29,27 @@ extension Vim {
     }
 
     public static func set(variable: String, value: VimScriptConvertible) {
-        command("let \(variable) = \(value.toVimScript())")
+        _ = try? command("let \(variable) = \(value.toVimScript())")
     }
 
     public static func get(variable: String) -> VimValue? {
-        return eval(variable)
+        return try? eval(variable)
     }
 
     public static func get(_ variable: String) -> VimValue? {
-        return eval(variable)
+        return try? eval(variable)
     }
 
     public static func get(_ variable: String) -> Bool {
-        return eval(variable)?.asBool() ?? false
+        return (try? eval(variable))?.asBool() ?? false
     }
 
     public static func get(_ variable: String) -> Int {
-        return eval(variable)?.asInt() ?? 0
+        return (try? eval(variable))?.asInt() ?? 0
     }
 
     public static func get(_ variable: String) -> String {
-        return eval(variable)?.asString() ?? ""
+        return (try? eval(variable))?.asString() ?? ""
     }
 
     /// Returns the 0-based current line and 0-based current column

Tests/VimKitTests/VimValueTest.swift

@@ -36,30 +36,30 @@ class VimValueTests: XCTestCase {
 
     func testEvalString() {
         swiftvim_initialize()
-        let result = Vim.eval("VALUE")!
+        let result = try! Vim.eval("VALUE")
         XCTAssertEqual(result.asString(), "VALUE")
         swiftvim_finalize()
     }
 
     func testCommandNone() {
         swiftvim_initialize()
-        let result = Vim.command("VALUE")!
+        let result = try! Vim.command("VALUE")
         XCTAssertNil(result.asString())
         swiftvim_finalize()
     }
 
     func testEvalInt() {
         swiftvim_initialize()
         mutateRuntime("eval", lambda: "lambda value : int(value)")
-        let result = Vim.eval("2")!
+        let result = try! Vim.eval("2")
         XCTAssertEqual(result.asInt(), 2)
         swiftvim_finalize()
     }
 
     func testEvalList() {
         swiftvim_initialize()
         mutateRuntime("eval", lambda: "lambda value : [1, 2]")
-        let result = Vim.eval("")!
+        let result = try! Vim.eval("")
         let list = result.asList()!
         XCTAssertEqual(list.count, 2)
         XCTAssertEqual(list[0].asInt(), 1)
@@ -72,7 +72,7 @@ class VimValueTests: XCTestCase {
     func testListCollectionUsage() {
         swiftvim_initialize()
         mutateRuntime("eval", lambda: "lambda value : [1, 2]")
-        let result = Vim.eval("")!
+        let result = try! Vim.eval("")
         let list = result.asList()!
         /// Smoke test we can do collectiony things.
         let incremented = list.map { $0.asInt()! + 1 }
@@ -83,7 +83,7 @@ class VimValueTests: XCTestCase {
     func testEvalDict() {
         swiftvim_initialize()
         mutateRuntime("eval", lambda: "lambda value : dict(a=42, b='a')")
-        let result = Vim.eval("")!
+        let result = try! Vim.eval("")
         let dict = result.asDictionary()!
         let aVal = dict["a"]!
         XCTAssertEqual(aVal.asInt()!, 42)
@@ -96,7 +96,7 @@ class VimValueTests: XCTestCase {
     func testDictCollectionUsage() {
         swiftvim_initialize()
         mutateRuntime("eval", lambda: "lambda value : dict(a=42, b='a')")
-        let result = Vim.eval("")!
+        let result = try! Vim.eval("")
         let dict = result.asDictionary()!
         XCTAssertEqual(dict.keys.count, 2)
         XCTAssertEqual(dict.values.count, 2)