Add configurable per-class log filtering

1 files changed, 63 insertions, 0 deletions

diff --git a/src/common/logging/filter.h b/src/common/logging/filter.h
new file mode 100644
index 00000000..32b14b15
--- /dev/null
+++ b/src/common/logging/filter.h
@@ -0,0 +1,63 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <array>
+#include <string>
+
+#include "common/logging/log.h"
+
+namespace Log {
+
+struct ClassInfo;
+
+/**
+ * Implements a log message filter which allows different log classes to have different minimum
+ * severity levels. The filter can be changed at runtime and can be parsed from a string to allow
+ * editing via the interface or loading from a configuration file.
+ */
+class Filter {
+public:
+    /// Initializes the filter with all classes having `default_level` as the minimum level.
+    Filter(Level default_level);
+
+    /// Resets the filter so that all classes have `level` as the minimum displayed level.
+    void ResetAll(Level level);
+    /// Sets the minimum level of `log_class` (and not of its subclasses) to `level`.
+    void SetClassLevel(Class log_class, Level level);
+    /**
+     * Sets the minimum level of all of `log_class` subclasses to `level`. The level of `log_class`
+     * itself is not changed.
+     */
+    void SetSubclassesLevel(const ClassInfo& log_class, Level level);
+
+    /**
+     * Parses a filter string and applies it to this filter.
+     *
+     * A filter string consists of a space-separated list of filter rules, each of the format
+     * `<class>:<level>`. `<class>` is a log class name, with subclasses separated using periods.
+     * A rule for a given class also affects all of its subclasses. `*` wildcards are allowed and
+     * can be used to apply a rule to all classes or to all subclasses of a class without affecting
+     * the parent class. `<level>` a severity level name which will be set as the minimum logging
+     * level of the matched classes. Rules are applied left to right, with each rule overriding
+     * previous ones in the sequence.
+     *
+     * A few examples of filter rules:
+     *  - `*:Info` -- Resets the level of all classes to Info.
+     *  - `Service:Info` -- Sets the level of Service and all subclasses (Service.FS, Service.APT,
+     *                       etc.) to Info.
+     *  - `Service.*:Debug` -- Sets the level of all Service subclasses to Debug, while leaving the
+     *                         level of Service unchanged.
+     *  - `Service.FS:Trace` -- Sets the level of the Service.FS class to Trace.
+     */
+    void ParseFilterString(const std::string& filter_str);
+    bool ParseFilterRule(const std::string::const_iterator start, const std::string::const_iterator end);
+
+    /// Matches class/level combination against the filter, returning true if it passed.
+    bool CheckMessage(Class log_class, Level level) const;
+
+private:
+    std::array<Level, (size_t)Class::Count> class_levels;
+};
+
+}