從R源文件中提取註釋，保留它們發生的功能

Question

我想從我的R源代碼腳本中提取註釋（與模式匹配），以保留它們發生的功能。

的目標是編寫使用經典的降價複選框- [ ]或- [x]內部函數體代碼文檔註釋，並提取作進一步處理這些意見作爲特徵向量的名單 - 我可以輕鬆編寫新.md文件。

下面是可重複使用的示例和預期輸出。

# preview the 'data' 
script_body = c('# some init comment - not matching pattern','g = function(){','# - [x] comment_g1','# - [ ] comment_g2','1','}','f = function(){','# - [ ] comment_f1','# another non match to pattern','g()+1','}') 
cat(script_body, sep = "\n") 
# # some init comment - not matching pattern 
# g = function(){ 
#  # - [x] comment_g1 
#  # - [ ] comment_g2 
#  1 
# } 
# f = function(){ 
#  # - [ ] comment_f1 
#  # another non match to pattern 
#  g()+1 
# } 

# populate R souce file 
writeLines(script_body, "test.R") 

# test it 
source("test.R") 
f() 
# [1] 2 

# expected output 
r = magic_function_get_comments("test.R", starts.with = c(" - [x] "," - [ ] ")) 
# r = list("g" = c(" - [x] comment_g1"," - [ ] comment_g2"), "f" = " - [ ] comment_f1") 
str(r) 
# List of 2 
# $ g: chr [1:2] " - [x] comment_g1" " - [ ] comment_g2" 
# $ f: chr " - [ ] comment_f1" 

Answer 1

這裏是一個精簡，未計算變種什麼hrbmstr做：

get_comments = function (filename) { 
    is_assign = function (expr) 
     as.character(expr) %in% c('<-', '<<-', '=', 'assign') 

    is_function = function (expr) 
     is.call(expr) && is_assign(expr[[1]]) && is.call(expr[[3]]) && expr[[3]][[1]] == quote(`function`) 

    source = parse(filename, keep.source = TRUE) 
    functions = Filter(is_function, source) 
    fun_names = as.character(lapply(functions, `[[`, 2)) 
    setNames(lapply(attr(functions, 'srcref'), grep, 
        pattern = '^\\s*#', value = TRUE), fun_names) 
} 

這配備了一個警告：因爲我們不評價的來源，我們可能會錯過函數定義（例如，我們不會找到f = local(function (x) x)）。上面的函數使用簡單的啓發式來查找函數定義（它將查看變量的function表達式的所有簡單賦值）。

這隻能使用eval（或source）修復，它帶有自己的警告 - 例如，執行來自未知來源的文件存在安全風險。

Answer 2

這是不太可能有人會寫的grep/stringr::str_match一部分，你（這不是一個咕嚕代碼編寫服務）。但是，對已解析的函數源進行迭代的習慣用法可能對更廣泛的受衆足夠有用，以保證包含。

CAVEAT這source() S中.R文件，這意味着它評估它。

#' Extract whole comment lines from an R source file 
#' 
#' \code{source()} an R source file into a temporary environment then 
#' iterate over the source of \code{function}s in that environment and 
#' \code{grep} out the whole line comments which can then be further 
#' processed. 
#' 
#' @param source_file path name to source file that \code{source()} will accept 
extract_comments <- function(source_file) { 

    tmp_env <- new.env(parent=sys.frame()) 
    source(source_file, tmp_env, echo=FALSE, print.eval=FALSE, verbose=FALSE, keep.source=TRUE) 
    funs <- Filter(is.function, sapply(ls(tmp_env), get, tmp_env)) 

    lapply(funs, function(f) { 
    # get function source 
    function_source <- capture.output(f) 
    # only get whole line comment lines 
    comments <- grep("^[[:blank:]]*#", function_source, value=TRUE) 
    # INCANT YOUR GREP/REGEX MAGIC HERE 
    # instead of just returning the comments 
    # since this isn't a free code-writing service 
    comments 
    }) 

} 

str(extract_comments("test.R")) 
## List of 2 
## $ f: chr [1:2] "# - [ ] comment_f1" "# another non match to pattern" 
## $ g: chr [1:2] "# - [x] comment_g1" "# - [ ] comment_g2"