HookMatcher R6 Class

Defines when a hook callback should be triggered. Hooks can be filtered by event type and optionally by tool name pattern.

Public fields

event

The hook event type (see HookEvent)

pattern

Optional regex pattern for tool name filtering

callback

The function to call when the hook fires

timeout

Maximum execution time for the callback in seconds

Methods

Public methods

• HookMatcher$new()

• HookMatcher$matches()

• HookMatcher$print()

• HookMatcher$clone()

---

Method new()

Create a new HookMatcher.

Usage

HookMatcher$new(event, callback, pattern = NULL, timeout = 30)

Arguments

event

The event type (must be one of HookEvent)

callback

Function to call. Signature depends on event type:

• PreToolUse: function(tool_name, tool_input, context)

• PostToolUse: function(tool_name, tool_result, tool_error, context)

• Stop: function(reason, context)

• SubagentStop: function(agent_name, task, result, context)

• UserPromptSubmit: function(prompt, context)

• PreCompact: function(turns_to_compact, turns_to_keep, context)

• SessionStart: function(context)

• SessionEnd: function(reason, context)

pattern

Optional regex pattern to filter by tool name. Only applies to PreToolUse and PostToolUse events.

timeout

Maximum callback execution time in seconds

Returns

A new HookMatcher object

Examples

\dontrun{
# Block dangerous bash commands
HookMatcher$new(
  event = "PreToolUse",
  pattern = "^(run_bash|bash)$",
  callback = function(tool_name, tool_input, context) {
    if (grepl("rm -rf", tool_input$command)) {
      HookResultPreToolUse(permission = "deny", reason = "Dangerous!")
    } else {
      HookResultPreToolUse(permission = "allow")
    }
  }
)
}

---

Method matches()

Check if this hook matches a given tool name.

Usage

HookMatcher$matches(tool_name = NULL)

Arguments

tool_name

The tool name to check (can be NULL)

Returns

Logical indicating if the hook matches

---

Method print()

Print the hook matcher.

Usage

HookMatcher$print()

---

Method clone()

The objects of this class are cloneable with this method.

Usage

HookMatcher$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

## ------------------------------------------------
## Method `HookMatcher$new`
## ------------------------------------------------

if (FALSE) { # \dontrun{
# Block dangerous bash commands
HookMatcher$new(
  event = "PreToolUse",
  pattern = "^(run_bash|bash)$",
  callback = function(tool_name, tool_input, context) {
    if (grepl("rm -rf", tool_input$command)) {
      HookResultPreToolUse(permission = "deny", reason = "Dangerous!")
    } else {
      HookResultPreToolUse(permission = "allow")
    }
  }
)
} # }