Implemented expression parsing

src/build/expression/Operator.go

@@ -0,0 +1,65 @@
+package expression
+
+import "git.akyoto.dev/cli/q/src/build/token"
+
+// Operator represents an operator for mathematical expressions.
+type Operator struct {
+	Symbol     string
+	Precedence int
+	Operands   int
+}
+
+// Operators defines the operators used in the language.
+// The number corresponds to the operator priority and can not be zero.
+var Operators = map[string]*Operator{
+	".":   {".", 12, 2},
+	"*":   {"*", 11, 2},
+	"/":   {"/", 11, 2},
+	"%":   {"%", 11, 2},
+	"+":   {"+", 10, 2},
+	"-":   {"-", 10, 2},
+	">>":  {">>", 9, 2},
+	"<<":  {"<<", 9, 2},
+	">":   {">", 8, 2},
+	"<":   {"<", 8, 2},
+	">=":  {">=", 8, 2},
+	"<=":  {"<=", 8, 2},
+	"==":  {"==", 7, 2},
+	"!=":  {"!=", 7, 2},
+	"&":   {"&", 6, 2},
+	"^":   {"^", 5, 2},
+	"|":   {"|", 4, 2},
+	"&&":  {"&&", 3, 2},
+	"||":  {"||", 2, 2},
+	"=":   {"=", 1, 2},
+	"+=":  {"+=", 1, 2},
+	"-=":  {"-=", 1, 2},
+	"*=":  {"*=", 1, 2},
+	"/=":  {"/=", 1, 2},
+	">>=": {">>=", 1, 2},
+	"<<=": {"<<=", 1, 2},
+}
+
+func isComplete(expr *Expression) bool {
+	if expr == nil {
+		return false
+	}
+
+	if expr.Token.Kind == token.Identifier {
+		return true
+	}
+
+	if expr.Token.Kind == token.Operator && len(expr.Children) == numOperands(expr.Token.Text()) {
+		return true
+	}
+
+	return false
+}
+
+func numOperands(symbol string) int {
+	return Operators[symbol].Operands
+}
+
+func precedence(symbol string) int {
+	return Operators[symbol].Precedence
+}