Method ParseExpressionToFilters

qrenderdoc/Windows/EventBrowser.cpp:3098–3665

};

ParseTrace EventFilterModel::ParseExpressionToFilters(QString expr, rdcarray<EventFilter> &filters) const
{
  // we have a simple grammar, we pick out subexpressions and they're all independent.
  //
  // - Individual words are literal subexpressions on their own and end with whitespace.
  // - A " starts a quoted literal subexpression, which is a literal string and ends on the next
  //   ". It supports escaping " with \ and otherwise any escaped character is the literal
  //   character. The quotes must be followed by whitespace or the end of the expression.
  // - Both literal subexpressions are matched case-insensitively. For case-sensitive matching
  //   you can use a regexp as a functional expression.
  // - A $ starts a functional expression, with parameters in brackets. The name starts with a
  //   letter and contains alphanumeric and . characters. The name is followed by a ( to begin the
  //   parameters and ends when the matching ) is found. Whitespace between the name and the ( is
  //   ignored, but any other character is a parse error. The ) must be followed by whitespace or
  //   the end of the expression or that's a parse error. Note that whitespace is allowed in the
  //   parameters.
  // - We allow nesting with simple () brackets. Unquoted literals cannot contain a ( to avoid
  //   parsing ambiguity between e.g. Foo(Bar Blah) and Foo (Bar Blah).
  //
  // This means there's a simple state machine we can follow from any point.
  //
  // 1) start -> whitespace -> start
  // 2) start -> " -> quoted_expression -> wait until unescaped " -> start
  // 3) start -> $ -> function_expression -> parse name > optional whitespace ->
  //             ( -> wait until matching parenthesis -> ) -> whitespace -> start
  // 4) start -> ( -> nested_expression -> wait until matching unquoted ) -> start
  // 5) start -> anything else -> literal -> wait until whitespace -> start
  //
  // We also have two modifiers:
  //
  // 6) start -> + -> note that next filter is a MustMatch -> start
  // 7) start -> - -> note that next filter is a CantMatch -> start
  //
  // any non-existant edge is a parse error

  ParseTrace trace;

  enum
  {
    Start,
    QuotedExpr,
    FunctionExprName,
    FunctionExprParams,
    Literal,
    Nested,
  } state = Start;

  expr = expr.trimmed();

  MatchType matchType = MatchType::Normal;

  // temporary string we're building up somewhere
  QString s;

  // parenthesis depth
  int parenDepth = 0;
  // start of the current set of parameters
  int paramStartPos = 0;