R Under development (unstable) (2023-11-19 r85561 ucrt) -- "Unsuffered Consequences"
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Platform: x86_64-w64-mingw32/x64

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> library(gtools)
> 
> ##############################
> ### Examples from man page ###
> ##############################
> 
> ### Toy examples
> 
> # search for x=10
> s <- binsearch(function(x) x - 10, range = c(0, 20))
> stopifnot(s$where == 10)
> 
> # search for x=10.1
> s <- binsearch(function(x) x - 10.1, range = c(0, 20))
> stopifnot(s$where == c(10, 11))
> 
> ### Classical toy example
> 
> # binary search for the index of 'M' among the sorted letters
> fun <- function(X) {
+   ifelse(LETTERS[X] > "M", 1,
+     ifelse(LETTERS[X] < "M", -1, 0)
+   )
+ }
> 
> s <- binsearch(fun, range = 1:26)
> stopifnot(LETTERS[s$where] == "M")
> 
> ##################################
> ### Test boundary contiditions ###
> ##################################
> 
> s <- binsearch(fun = function(x) x - 10, range = c(1, 10))
> with(s, stopifnot(where == 10, value == 0, flag == "Found"))
> 
> s <- binsearch(fun = function(x) x - 1, range = c(1, 10))
> with(s, stopifnot(where == 1, value == 0, flag == "Found"))
> 
> 
> checkWarning <- function(expr) {
+   myEnv <- environment()
+ 
+   catchWarning <- function(w) {
+     assign("warningValue", w, pos = myEnv)
+     invokeRestart("muffleWarning")
+   }
+ 
+   retval <- withCallingHandlers(
+     expr = expr,
+     warning = catchWarning
+   )
+ 
+ 
+   if (!exists("warningValue", where = myEnv, inherits = FALSE)) {
+     stop("Expected a warning message")
+   }
+ }
> 
> checkWarning(s <- binsearch(fun = function(x) x - 10, range = c(1, 9)))
> with(s, stopifnot(where == 9, value == -1, flag == "Upper Boundary"))
> 
> checkWarning(s <- binsearch(fun = function(x) x - 1, range = c(2, 10)))
> with(s, stopifnot(where == 2, value == 1, flag == "Lower Boundary"))
> 
> proc.time()
   user  system elapsed 
   0.18    0.12    0.29