func()

in promql/parser/parse.go [437:623]
149 lines of code
73 McCabe index (conditional complexity)

func (p *parser) checkAST(node Node) (typ ValueType) {
	// For expressions the type is determined by their Type function.
	// Lists do not have a type but are not invalid either.
	switch n := node.(type) {
	case Expressions:
		typ = ValueTypeNone
	case Expr:
		typ = n.Type()
	default:
		p.addParseErrf(node.PositionRange(), "unknown node type: %T", node)
	}

	// Recursively check correct typing for child nodes and raise
	// errors in case of bad typing.
	switch n := node.(type) {
	case *EvalStmt:
		ty := p.checkAST(n.Expr)
		if ty == ValueTypeNone {
			p.addParseErrf(n.Expr.PositionRange(), "evaluation statement must have a valid expression type but got %s", DocumentedType(ty))
		}

	case Expressions:
		for _, e := range n {
			ty := p.checkAST(e)
			if ty == ValueTypeNone {
				p.addParseErrf(e.PositionRange(), "expression must have a valid expression type but got %s", DocumentedType(ty))
			}
		}
	case *AggregateExpr:
		if !n.Op.IsAggregator() {
			p.addParseErrf(n.PositionRange(), "aggregation operator expected in aggregation expression but got %q", n.Op)
		}
		p.expectType(n.Expr, ValueTypeVector, "aggregation expression")
		if n.Op == TOPK || n.Op == BOTTOMK || n.Op == QUANTILE {
			p.expectType(n.Param, ValueTypeScalar, "aggregation parameter")
		}
		if n.Op == COUNT_VALUES {
			p.expectType(n.Param, ValueTypeString, "aggregation parameter")
		}

	case *BinaryExpr:
		lt := p.checkAST(n.LHS)
		rt := p.checkAST(n.RHS)

		// opRange returns the PositionRange of the operator part of the BinaryExpr.
		// This is made a function instead of a variable, so it is lazily evaluated on demand.
		opRange := func() (r PositionRange) {
			// Remove whitespace at the beginning and end of the range.
			for r.Start = n.LHS.PositionRange().End; isSpace(rune(p.lex.input[r.Start])); r.Start++ { // nolint:revive
			}
			for r.End = n.RHS.PositionRange().Start - 1; isSpace(rune(p.lex.input[r.End])); r.End-- { // nolint:revive
			}
			return
		}

		if n.ReturnBool && !n.Op.IsComparisonOperator() {
			p.addParseErrf(opRange(), "bool modifier can only be used on comparison operators")
		}

		if n.Op.IsComparisonOperator() && !n.ReturnBool && n.RHS.Type() == ValueTypeScalar && n.LHS.Type() == ValueTypeScalar {
			p.addParseErrf(opRange(), "comparisons between scalars must use BOOL modifier")
		}

		if n.Op.IsSetOperator() && n.VectorMatching.Card == CardOneToOne {
			n.VectorMatching.Card = CardManyToMany
		}

		for _, l1 := range n.VectorMatching.MatchingLabels {
			for _, l2 := range n.VectorMatching.Include {
				if l1 == l2 && n.VectorMatching.On {
					p.addParseErrf(opRange(), "label %q must not occur in ON and GROUP clause at once", l1)
				}
			}
		}

		if !n.Op.IsOperator() {
			p.addParseErrf(n.PositionRange(), "binary expression does not support operator %q", n.Op)
		}
		if lt != ValueTypeScalar && lt != ValueTypeVector {
			p.addParseErrf(n.LHS.PositionRange(), "binary expression must contain only scalar and instant vector types")
		}
		if rt != ValueTypeScalar && rt != ValueTypeVector {
			p.addParseErrf(n.RHS.PositionRange(), "binary expression must contain only scalar and instant vector types")
		}

		switch {
		case (lt != ValueTypeVector || rt != ValueTypeVector) && n.VectorMatching != nil:
			if len(n.VectorMatching.MatchingLabels) > 0 {
				p.addParseErrf(n.PositionRange(), "vector matching only allowed between instant vectors")
			}
			n.VectorMatching = nil
		case n.Op.IsSetOperator(): // Both operands are Vectors.
			if n.VectorMatching.Card == CardOneToMany || n.VectorMatching.Card == CardManyToOne {
				p.addParseErrf(n.PositionRange(), "no grouping allowed for %q operation", n.Op)
			}
			if n.VectorMatching.Card != CardManyToMany {
				p.addParseErrf(n.PositionRange(), "set operations must always be many-to-many")
			}
		}

		if (lt == ValueTypeScalar || rt == ValueTypeScalar) && n.Op.IsSetOperator() {
			p.addParseErrf(n.PositionRange(), "set operator %q not allowed in binary scalar expression", n.Op)
		}

	case *Call:
		nargs := len(n.Func.ArgTypes)
		if n.Func.Variadic == 0 {
			if nargs != len(n.Args) {
				p.addParseErrf(n.PositionRange(), "expected %d argument(s) in call to %q, got %d", nargs, n.Func.Name, len(n.Args))
			}
		} else {
			na := nargs - 1
			if na > len(n.Args) {
				p.addParseErrf(n.PositionRange(), "expected at least %d argument(s) in call to %q, got %d", na, n.Func.Name, len(n.Args))
			} else if nargsmax := na + n.Func.Variadic; n.Func.Variadic > 0 && nargsmax < len(n.Args) {
				p.addParseErrf(n.PositionRange(), "expected at most %d argument(s) in call to %q, got %d", nargsmax, n.Func.Name, len(n.Args))
			}
		}

		for i, arg := range n.Args {
			if i >= len(n.Func.ArgTypes) {
				if n.Func.Variadic == 0 {
					// This is not a vararg function so we should not check the
					// type of the extra arguments.
					break
				}
				i = len(n.Func.ArgTypes) - 1
			}
			p.expectType(arg, n.Func.ArgTypes[i], fmt.Sprintf("call to function %q", n.Func.Name))
		}

	case *ParenExpr:
		p.checkAST(n.Expr)

	case *UnaryExpr:
		if n.Op != ADD && n.Op != SUB {
			p.addParseErrf(n.PositionRange(), "only + and - operators allowed for unary expressions")
		}
		if t := p.checkAST(n.Expr); t != ValueTypeScalar && t != ValueTypeVector {
			p.addParseErrf(n.PositionRange(), "unary expression only allowed on expressions of type scalar or instant vector, got %q", DocumentedType(t))
		}

	case *SubqueryExpr:
		ty := p.checkAST(n.Expr)
		if ty != ValueTypeVector {
			p.addParseErrf(n.PositionRange(), "subquery is only allowed on instant vector, got %s instead", ty)
		}
	case *MatrixSelector:
		p.checkAST(n.VectorSelector)

	case *VectorSelector:
		if n.Name != "" {
			// In this case the last LabelMatcher is checking for the metric name
			// set outside the braces. This checks if the name has already been set
			// previously.
			for _, m := range n.LabelMatchers[0 : len(n.LabelMatchers)-1] {
				if m != nil && m.Name == labels.MetricName {
					p.addParseErrf(n.PositionRange(), "metric name must not be set twice: %q or %q", n.Name, m.Value)
				}
			}

			// Skip the check for non-empty matchers because an explicit
			// metric name is a non-empty matcher.
			break
		}

		// A Vector selector must contain at least one non-empty matcher to prevent
		// implicit selection of all metrics (e.g. by a typo).
		notEmpty := false
		for _, lm := range n.LabelMatchers {
			if lm != nil && !lm.Matches("") {
				notEmpty = true
				break
			}
		}
		if !notEmpty {
			p.addParseErrf(n.PositionRange(), "vector selector must contain at least one non-empty matcher")
		}

	case *NumberLiteral, *StringLiteral:
		// Nothing to do for terminals.

	default:
		p.addParseErrf(n.PositionRange(), "unknown node type: %T", node)
	}
	return
}