View Source iif (etran v0.5.2)
Conditional expression functions
This module exports a parse transform and implements several condition-checking functions.
When using this as a parse transform, include the{parse_transform,iif} compiler option. In this case for given expressions A,B,C, and D the following code transforms will be done: iif(A, B) -> case A of true -> B; _ -> undefined end
iif(A, B, C) -> case A of true -> B; _ -> C end
iif(A,B,C,D) -> case A of B -> C; _ -> D end
nvl(A,B) -> case A of false -> B; undefined -> B; [] -> B; _ -> A end
nvl(A,B,C) -> case A of false -> B; undefined -> B; [] -> B; _ -> C endiif_debug command-line option: erlc -Diif_debug=1 ... % Prints AST before the transform
erlc -Diif_debug=2 ... % Prints AST after the transform
erlc -Diif_debug[=3] ... % Prints AST before/after the transformiif/3,4 exported functions that can be used without the transform.
Link to this section Summary
Functions
Format if first argument is not empty
Return
Value if first argument is one of: [], false, undefined. Otherwise return the value of the first argument.Return
Empty if first argument is one of: [], false, undefined. Otherwise, if NotEmpty is fun(), evaluate it, or if it's fun(Arg) evaluate it with Value argument.Return
Value if first argument is not one of: [], false, undefined. Otherwise, if Value is fun(), evaluate it, or if it's fun(Arg) evaluate it with Test argument. If not emptyReturn
NotEmpty if first argument is not one of: [], false, undefined. Otherwise, if NotEmpty is fun(), evaluate it, or if it's fun(Arg) evaluate it with Value argument.Return
True if first argument is true or return False if the first argument is one of: [], false, undefined.Return
True if first two arguments matchAlias for
ife/2Parse transform to be used by providing
{parse_transform, iif} option. Opts are compiler options passed from command line. E.g.: erlc -Diif_ast ... -> Opts = [{d,iif_ast}|_]
erlc -Diif_orig ... -> Opts = [{d,iif_orig}|_]
erlc -Diif_src ... -> Opts = [{d,iif_src}|_]Link to this section Functions
Value if first argument is one of: [], false, undefined. Otherwise return the value of the first argument.
Empty if first argument is one of: [], false, undefined. Otherwise, if NotEmpty is fun(), evaluate it, or if it's fun(Arg) evaluate it with Value argument.
Value if first argument is not one of: [], false, undefined. Otherwise, if Value is fun(), evaluate it, or if it's fun(Arg) evaluate it with Test argument. If not empty
NotEmpty if first argument is not one of: [], false, undefined. Otherwise, if NotEmpty is fun(), evaluate it, or if it's fun(Arg) evaluate it with Value argument.
True if first argument is true or return False if the first argument is one of: [], false, undefined.
True if first two arguments match
ife/2
{parse_transform, iif} option. Opts are compiler options passed from command line. E.g.: erlc -Diif_ast ... -> Opts = [{d,iif_ast}|_]
erlc -Diif_orig ... -> Opts = [{d,iif_orig}|_]
erlc -Diif_src ... -> Opts = [{d,iif_src}|_]