Merge pull request 'implement-reserved-identifiers' (#76) from implement-reserved-identifiers into main

Reviewed-on: #76

analyzer/control-flow_test.go

@@ -103,7 +103,7 @@ U: (| Int F64 UInt)
 func TestSwitch (test *testing.T) {
 testString (test,
 `
-[switch x:Int]:Int = switch x
+[f x:Int]:Int = switch x
 	| 0 5
 	| 1 4
 	| 2 3
@@ -134,7 +134,7 @@ func TestSwitchErrBadLiteral (test *testing.T) {
 testStringErr (test,
 "cannot use array literal as Int", 4, 4,
 `
-[switch x:Int]:Int = switch x
+[f x:Int]:Int = switch x
 	| 0 5
 	| (1) 4
 	| 2 3
@@ -146,7 +146,7 @@ func TestSwitchErrNotConstant (test *testing.T) {
 testStringErr (test,
 "y cannot represent a constant integer", 7, 4,
 `
-[switch x:Int]:Int = {
+[f x:Int]:Int = {
 	y:Int = 1
 
 	switch x
@@ -162,7 +162,7 @@ func TestSwitchErrDuplicate (test *testing.T) {
 testStringErr (test,
 "65 already listed in match at stream0.fspl:6:2", 7, 4,
 `
-[switch x:I8]:Int = switch x
+[f x:I8]:Int = switch x
 	| 0   5
 	| 1   4
 	| 2   3

analyzer/expression.go

@@ -3,6 +3,7 @@ package analyzer
 import "fmt"
 import "git.tebibyte.media/fspl/fspl/errors"
 import "git.tebibyte.media/fspl/fspl/entity"
+import "git.tebibyte.media/fspl/fspl/parser/fspl"
 
 // All expression analysis routines must take in the type they are being
 // assigned to and return an error if they can't be assigned to it. if the type
@@ -62,6 +63,13 @@ func (this *Tree) analyzeDeclaration (
 	entity.Expression,
 	error,
 ) {
+	if fsplParser.IsReserved(declaration.Name) {
+		return nil, errors.Errorf (
+			declaration.Position(),
+			"cannot shadow reserved identifier %s",
+			declaration.Name)
+	}
+
 	scope, _ := this.topScope()
 	existing := scope.Variable(declaration.Name)
 	if existing != nil {

analyzer/tree.go

@@ -76,6 +76,11 @@ func (this *Tree) assembleRawMaps () error {
 }
 
 func (this *Tree) topLevelNameAvailable (currentPos errors.Position, key entity.Key) error {
+	if fsplParser.IsReserved(key.Name) {
+		return errors.Errorf (
+			currentPos, "cannot shadow reserved identifier %s",
+			key.Name)
+	}
 	if _, isPrimitive := primitiveTypes[key.Name]; isPrimitive {
 		return errors.Errorf (
 			currentPos, "cannot shadow primitive %s",

parser/fspl/reserved.go

@@ -0,0 +1,13 @@
+package fsplParser
+
+func IsReserved (identifier string) bool {
+	switch identifier {
+	case "true", "false", "nil",
+		"if", "match", "switch",
+		"loop", "for",
+		"then", "in",
+		"break", "return":
+		return true
+	default: return false
+	}
+}