Implemented compilation to SSA form

src/core/Evaluate.go

@@ -0,0 +1,84 @@
+package core
+
+import (
+	"fmt"
+
+	"git.urbach.dev/cli/q/src/errors"
+	"git.urbach.dev/cli/q/src/expression"
+	"git.urbach.dev/cli/q/src/ssa"
+	"git.urbach.dev/cli/q/src/token"
+)
+
+// Evaluate converts an expression to an SSA value.
+func (f *Function) Evaluate(expr *expression.Expression) (*ssa.Value, error) {
+	if expr.IsLeaf() {
+		switch expr.Token.Kind {
+		case token.Identifier:
+			name := expr.Token.String(f.File.Bytes)
+			value, exists := f.Identifiers[name]
+
+			if !exists {
+				return nil, errors.New(&UnknownIdentifier{Name: name}, f.File, expr.Token.Position)
+			}
+
+			return value, nil
+
+		case token.Number:
+			number, err := f.ToNumber(expr.Token)
+
+			if err != nil {
+				return nil, err
+			}
+
+			return f.AppendInt(number), nil
+
+		case token.String:
+			data := expr.Token.Bytes(f.File.Bytes)
+			data = Unescape(data)
+			return f.AppendBytes(data), nil
+		}
+
+		return nil, errors.New(InvalidExpression, f.File, expr.Token.Position)
+	}
+
+	switch expr.Token.Kind {
+	case token.Call:
+		children := expr.Children
+		typ := ssa.Call
+
+		if children[0].Token.Kind == token.Identifier {
+			funcName := children[0].String(f.File.Bytes)
+
+			if funcName == "len" {
+				identifier := children[1].String(f.File.Bytes)
+				return f.Identifiers[identifier+".length"], nil
+			}
+
+			if funcName == "syscall" {
+				children = children[1:]
+				typ = ssa.Syscall
+			}
+		}
+
+		args := make([]*ssa.Value, len(children))
+
+		for i, child := range children {
+			value, err := f.Evaluate(child)
+
+			if err != nil {
+				return nil, err
+			}
+
+			args[i] = value
+		}
+
+		call := f.Append(ssa.Value{Type: typ, Args: args})
+		return call, nil
+
+	case token.Dot:
+		name := fmt.Sprintf("%s.%s", expr.Children[0].String(f.File.Bytes), expr.Children[1].String(f.File.Bytes))
+		return f.AppendFunction(name), nil
+	}
+
+	return nil, nil
+}