Implemented function scanning

src/errors/Common.go

@@ -0,0 +1,14 @@
+package errors
+
+var (
+	ExpectedFunctionDefinition = &String{"Expected function definition"}
+	ExpectedPackageName        = &String{"Expected package name"}
+	InvalidDefinition          = &String{"Invalid definition"}
+	MissingBlockStart          = &String{"Missing '{'"}
+	MissingBlockEnd            = &String{"Missing '}'"}
+	MissingGroupStart          = &String{"Missing '('"}
+	MissingGroupEnd            = &String{"Missing ')'"}
+	MissingParameter           = &String{"Missing parameter"}
+	MissingType                = &String{"Missing type"}
+	NoInputFiles               = &String{"No input files"}
+)

src/errors/InvalidCharacter.go

@@ -0,0 +1,13 @@
+package errors
+
+import "fmt"
+
+// InvalidCharacter is created when an invalid character appears.
+type InvalidCharacter struct {
+	Character string
+}
+
+// Error implements the error interface.
+func (err *InvalidCharacter) Error() string {
+	return fmt.Sprintf("Invalid character '%s'", err.Character)
+}

src/errors/InvalidTopLevel.go

@@ -0,0 +1,13 @@
+package errors
+
+import "fmt"
+
+// InvalidTopLevel error is created when a top-level instruction is not valid.
+type InvalidTopLevel struct {
+	Instruction string
+}
+
+// Error implements the error interface.
+func (err *InvalidTopLevel) Error() string {
+	return fmt.Sprintf("Invalid top level instruction '%s'", err.Instruction)
+}

src/errors/IsNotDirectory.go

@@ -0,0 +1,13 @@
+package errors
+
+import "fmt"
+
+// IsNotDirectory error is created when a path is not a directory.
+type IsNotDirectory struct {
+	Path string
+}
+
+// Error implements the error interface.
+func (err *IsNotDirectory) Error() string {
+	return fmt.Sprintf("'%s' is not a directory", err.Path)
+}