From 544fe257004ac35ae4c57dab77f8b9f18a73db2a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stanis=C5=82aw=20Barzowski?= <sbarzowski@google.com>
Date: Tue, 26 Sep 2017 17:55:14 -0400
Subject: [PATCH] Simplistic argument checking

To be expanded when optional arguments arrive.
---
 testdata/bad_function_call.golden            |  1 +
 testdata/bad_function_call.jsonnet           |  1 +
 testdata/bad_function_call2.golden           |  1 +
 testdata/bad_function_call2.jsonnet          |  1 +
 testdata/bad_function_call_and_error.golden  |  1 +
 testdata/bad_function_call_and_error.jsonnet |  1 +
 thunks.go                                    |  5 ++++-
 value.go                                     | 10 ++++++++++
 8 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 testdata/bad_function_call.golden
 create mode 100644 testdata/bad_function_call.jsonnet
 create mode 100644 testdata/bad_function_call2.golden
 create mode 100644 testdata/bad_function_call2.jsonnet
 create mode 100644 testdata/bad_function_call_and_error.golden
 create mode 100644 testdata/bad_function_call_and_error.jsonnet

diff --git a/testdata/bad_function_call.golden b/testdata/bad_function_call.golden
new file mode 100644
index 0000000..7ec1af3
--- /dev/null
+++ b/testdata/bad_function_call.golden
@@ -0,0 +1 @@
+RUNTIME ERROR: function expected 1 argument(s), but got 0
diff --git a/testdata/bad_function_call.jsonnet b/testdata/bad_function_call.jsonnet
new file mode 100644
index 0000000..e56145a
--- /dev/null
+++ b/testdata/bad_function_call.jsonnet
@@ -0,0 +1 @@
+(function(x) x)()
diff --git a/testdata/bad_function_call2.golden b/testdata/bad_function_call2.golden
new file mode 100644
index 0000000..83f8a45
--- /dev/null
+++ b/testdata/bad_function_call2.golden
@@ -0,0 +1 @@
+RUNTIME ERROR: function expected 1 argument(s), but got 2
diff --git a/testdata/bad_function_call2.jsonnet b/testdata/bad_function_call2.jsonnet
new file mode 100644
index 0000000..73668d7
--- /dev/null
+++ b/testdata/bad_function_call2.jsonnet
@@ -0,0 +1 @@
+(function(x) x)(1, 2)
diff --git a/testdata/bad_function_call_and_error.golden b/testdata/bad_function_call_and_error.golden
new file mode 100644
index 0000000..83f8a45
--- /dev/null
+++ b/testdata/bad_function_call_and_error.golden
@@ -0,0 +1 @@
+RUNTIME ERROR: function expected 1 argument(s), but got 2
diff --git a/testdata/bad_function_call_and_error.jsonnet b/testdata/bad_function_call_and_error.jsonnet
new file mode 100644
index 0000000..1605d30
--- /dev/null
+++ b/testdata/bad_function_call_and_error.jsonnet
@@ -0,0 +1 @@
+(function(x) x)(error "x", error "y")
diff --git a/thunks.go b/thunks.go
index 759f4e6..b62b183 100644
--- a/thunks.go
+++ b/thunks.go
@@ -80,7 +80,10 @@ func makeCallThunk(ec evalCallable, args callArguments) potentialValue {
 
 func (th *callThunk) getValue(i *interpreter, trace *TraceElement) (value, error) {
 	evaluator := makeEvaluator(i, trace)
-	// TODO(sbarzowski): actually this trace is kinda useless inside...
+	err := checkArguments(evaluator, th.args, th.function.Parameters())
+	if err != nil {
+		return nil, err
+	}
 	return th.function.EvalCall(th.args, evaluator)
 }
 
diff --git a/value.go b/value.go
index f514f49..2a2a7ec 100644
--- a/value.go
+++ b/value.go
@@ -244,6 +244,16 @@ func (f *valueFunction) parameters() ast.Identifiers {
 	return f.ec.Parameters()
 }
 
+func checkArguments(e *evaluator, args callArguments, params ast.Identifiers) error {
+	// TODO(sbarzowski) this will get much more complicated with named params
+	numPassed := len(args.positional)
+	numExpected := len(params)
+	if numPassed != numExpected {
+		return e.Error(fmt.Sprintf("function expected %v argument(s), but got %v", numExpected, numPassed))
+	}
+	return nil
+}
+
 func (f *valueFunction) typename() string {
 	return "function"
 }