Increment a counter value

Increments an Automerge counter by the specified delta. Counters are CRDT types that support concurrent increments from multiple actors. Unlike regular integers, counter increments are commutative and do not conflict when merged.

Usage

am_counter_increment(doc, obj, key, delta)

Arguments

doc

An Automerge document

obj

An Automerge object ID (map or list), or AM_ROOT for the document root

key

For maps: a character string key. For lists: an integer index (1-based)

delta

Integer value to add to the counter (can be negative)

Value

The document (invisibly), allowing for chaining with pipes

Details

The delta can be negative to decrement the counter.

Examples

# Counter in document root (map)
doc <- am_create()
doc$score <- am_counter(0)
am_counter_increment(doc, AM_ROOT, "score", 10)
doc$score  # 10
#> <Automerge Counter: 10 >

am_counter_increment(doc, AM_ROOT, "score", 5)
doc$score  # 15
#> <Automerge Counter: 15 >

# Decrement with negative delta
am_counter_increment(doc, AM_ROOT, "score", -3)
doc$score  # 12
#> <Automerge Counter: 12 >

# Counter in a nested map
doc$stats <- am_map(views = am_counter(0))
stats_obj <- doc$stats
am_counter_increment(doc, stats_obj, "views", 100)

# Counter in a list (1-based indexing)
doc$counters <- list(am_counter(0), am_counter(5))
counters_obj <- doc$counters
am_counter_increment(doc, counters_obj, 1, 1)  # Increment first counter
am_counter_increment(doc, counters_obj, 2, 2)  # Increment second counter