expressionevaluator.h File Reference

Minimal SQL-flavoured expression evaluator for the RuleBasedRenderer. Slice X.25. More...

#include <QString>
#include <QVariantMap>

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Classes
class	OpenSWMM::Render::ExpressionEvaluator

Namespaces
namespace	OpenSWMM
namespace	OpenSWMM::Render

Detailed Description

Minimal SQL-flavoured expression evaluator for the RuleBasedRenderer. Slice X.25.

Author

Caleb Buahin caleb.nosp@m..bua.nosp@m.hin@g.nosp@m.mail.nosp@m..com

Date

2026

License\n GPL-3.0-or-later

Goal: cover the QGIS / SQL-WHERE common cases so styles authored externally evaluate correctly, without rebuilding a full expression language.

Grammar (informal): expr ::= or or ::= and ( "OR" and )* and ::= not ( "AND" not )* not ::= "NOT" not | comparison comp ::= primary [ ("=" | "!=" | "<>" | "<" | "<=" | ">" | ">=") primary | "IS" ["NOT"] "NULL" | "LIKE" string ] primary ::= number | string | identifier | "(" expr ")"

Strings: single-quoted, with "''" as embedded quote. Numbers: integer or decimal, no exponent. Identifiers: bare attribute names — read out of the QVariantMap by the same key.

The eval function returns true on match, false otherwise; malformed expressions return false and a non-empty error string in lastError().