A comprehension expression applied to a list or map. Comprehensions are not part of the core syntax, but enabled with macros. A macro matches a specific call signature within a parsed AST and replaces the call with an alternate AST block. Macro expansion happens at parse time. The following macros are supported within CEL: Aggregate type macros may be applied to all elements in a list or all keys in a map: * all, exists, exists_one - test a predicate expression against the inputs and return true if the predicate is satisfied for all, any, or only one value list.all(x, x < 10). * filter - test a predicate expression against the inputs and return the subset of elements which satisfy the predicate: payments.filter(p, p > 1000). * map - apply an expression to all elements in the input and return the output aggregate type: [1, 2, 3].map(i, i * i). The has(m.x) macro tests whether the property x is present in struct m. The semantics of this macro depend on the type of m. For proto2 messages has(m.x) is defined as 'defined, but not set. For proto3, the macro tests whether the property is set to its default. For map and struct types, the macro tests whether the property xis defined onm. Comprehensions for the standard environment macros evaluation can be best visualized as the following pseudocode: ``` let accu_var=accu_initfor (letiter_variniter_range) { if (!loop_condition) { break } accu_var=loop_step} returnresult``` Comprehensions for the optional V2 macros which support map-to-map translation differ slightly from the standard environment macros in that they expose both the key or index in addition to the value for each list or map entry: ``` letaccu_var=accu_initfor (letiter_var, iter_var2initer_range) { if (!loop_condition) { break } accu_var=loop_step} returnresult` ```
| Name | Type | Description | Notes |
|---|---|---|---|
| iterVar | String | The name of the first iteration variable. When the iter_range is a list, this variable is the list element. When the iter_range is a map, this variable is the map entry key. | [optional] |
| iterVar2 | String | The name of the second iteration variable, empty if not set. When the iter_range is a list, this variable is the integer index. When the iter_range is a map, this variable is the map entry value. This field is only set for comprehension v2 macros. | [optional] |
| iterRange | Expr | [optional] | |
| accuVar | String | The name of the variable used for accumulation of the result. | [optional] |
| accuInit | Expr | [optional] | |
| loopCondition | Expr | [optional] | |
| loopStep | Expr | [optional] | |
| result | Expr | [optional] |