*! _kmplot_times Version 1.0.0  2026/10/20
*! Expand numeric time lists without rounding explicit double values
*! Author: Timothy P Copeland, Karolinska Institutet
*! Program class: rclass

/*
Returns r(times): the requested times, sorted, duplicates dropped, each in
the shortest decimal text that reads back as the same double.

Typed values keep their full double precision.  A member generated by a
range (start + j * step, j > 0) carries the arithmetic error of that sum
(3 * 0.1 = 0.30000000000000004); it is replaced by its 15-significant-digit
value, the decimal the range stands for, so 0(0.1)1 and the typed list
0 .1 ... 1 give the same doubles.

With stmatch, also returns r(cmptimes): for each time in r(times), the value
to compare with _t.  When the stset base time variable is stored as float
and stset's transform _t = (time - origin) / scale (constant origin and
scale) reproduces _t on every event record, a requested time tp is compared
at the data's float precision: (float(tp * scale + origin) - origin) / scale,
which is exactly the _t of a record whose time variable holds float(tp).
Otherwise r(cmptimes) equals r(times).
*/

program define _kmplot_times, rclass
    version 16.0
    local _orig_varabbrev = c(varabbrev)
    set varabbrev off
    capture noisily {
        syntax , VALues(string) [STMatch]
        * Stata validates grammar and cardinality; its decimal serialization
        * is used only to count sequence members, never as the requested time.
        numlist "`values'"
        tokenize "`values'", parse(" /()[]:")
        local times ""
        tempname start step value v15
        while "`1'" != "" {
            scalar `start' = `1'
            scalar `step' = 1
            local n = 1
            if inlist("`2'", "(", "[") {
                scalar `step' = `3'
                numlist "`1'(`3')`5'"
                local n : word count `r(numlist)'
                macro shift 5
            }
            else if "`2'" == "/" {
                numlist "`1'/`3'"
                local n : word count `r(numlist)'
                if `3' < scalar(`start') scalar `step' = -1
                macro shift 3
            }
            else if inlist("`3'", ":", "to") {
                scalar `step' = `2' - scalar(`start')
                numlist "`1' `2' to `4'"
                local n : word count `r(numlist)'
                macro shift 4
            }
            else {
                macro shift
            }
            forvalues j = 0/`=`n' - 1' {
                scalar `value' = scalar(`start') + `j' * scalar(`step')
                if `j' > 0 {
                    scalar `v15' = real(string(scalar(`value'), "%21.15g"))
                    if abs(scalar(`v15') - scalar(`value')) <= ///
                        1e-9 * abs(scalar(`step')) {
                        scalar `value' = scalar(`v15')
                    }
                }
                local text : display %24.17g scalar(`value')
                local times "`times' `text'"
            }
        }
        mata: st_local("times", invtokens(strofreal(uniqrows(strtoreal(tokens(st_local("times")))')', "%24.17g")))
        * Each value in the shortest of %21.15g, %21.16g and %24.17g that
        * reads back as the same double.
        local _short ""
        foreach _x of local times {
            local _sx "`_x'"
            forvalues _k = 16(-1)15 {
                local _try : display %21.`_k'g `_x'
                local _try = strtrim("`_try'")
                if real("`_try'") == `_x' local _sx "`_try'"
            }
            local _short "`_short' `_sx'"
        }
        local times = strtrim("`_short'")
        local cmptimes "`times'"
        if "`stmatch'" != "" {
            local _bt : char _dta[st_bt]
            local _o : char _dta[st_o]
            local _s : char _dta[st_s]
            local _map = 0
            capture confirm numeric variable `_bt', exact
            if _rc == 0 {
                if "`: type `_bt''" == "float" {
                    capture confirm number `_o'
                    local _map = (_rc == 0)
                    capture confirm number `_s'
                    if _rc local _map = 0
                }
            }
            if `_map' {
                quietly count if _d == 1 & _t != (`_bt' - (`_o')) / (`_s')
                if r(N) == 0 {
                    mata: st_local("cmptimes", invtokens(strofreal( ///
                        (floatround(strtoreal(tokens(st_local("times"))) ///
                        :* strtoreal(st_local("_s")) :+ strtoreal(st_local("_o"))) ///
                        :- strtoreal(st_local("_o"))) :/ strtoreal(st_local("_s")), ///
                        "%24.17g")))
                }
            }
        }
    }
    local rc = _rc
    set varabbrev `_orig_varabbrev'
    if `rc' exit `rc'
    return local times "`times'"
    if "`stmatch'" != "" return local cmptimes "`cmptimes'"
end