Implemented if statements

src/build/core/CompileIf.go

@@ -0,0 +1,48 @@
+package core
+
+import (
+	"fmt"
+
+	"git.akyoto.dev/cli/q/src/build/asm"
+	"git.akyoto.dev/cli/q/src/build/ast"
+)
+
+// CompileIf compiles a branch instruction.
+func (f *Function) CompileIf(branch *ast.If) error {
+	condition := branch.Condition
+	tmpRight := f.cpu.Input[1]
+	err := f.ExpressionToRegister(condition.Children[1], tmpRight)
+
+	if err != nil {
+		return err
+	}
+
+	tmpLeft := f.cpu.Input[0]
+	err = f.ExpressionToRegister(condition.Children[0], tmpLeft)
+
+	if err != nil {
+		return err
+	}
+
+	f.assembler.RegisterRegister(asm.COMPARE, tmpLeft, tmpRight)
+	elseLabel := fmt.Sprintf("%s_if_%d_else", f.Name, f.count.branch)
+
+	switch condition.Token.Text() {
+	case "==":
+		f.assembler.Label(asm.JNE, elseLabel)
+	case "!=":
+		f.assembler.Label(asm.JE, elseLabel)
+	case ">":
+		f.assembler.Label(asm.JLE, elseLabel)
+	case "<":
+		f.assembler.Label(asm.JGE, elseLabel)
+	case ">=":
+		f.assembler.Label(asm.JL, elseLabel)
+	case "<=":
+		f.assembler.Label(asm.JG, elseLabel)
+	}
+
+	defer f.assembler.Label(asm.LABEL, elseLabel)
+	f.count.branch++
+	return f.CompileAST(branch.Body)
+}