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# generate spaces of width n
spaces = function(n = 1, char = ' ') {
if (n <= 0) return('')
if (n == 1) return(char)
paste(rep(char, n), collapse = '')
}
# group source lines into complete expressions (using a brutal-force method)
group_src = function(code) {
if ((n <- length(code)) < 1) return(list(code))
i = i1 = i2 = 1
x = list()
while (i2 <= n) {
piece = code[i1:i2]
if (try_parse(piece)) {
x[[i]] = piece; i = i + 1
i1 = i2 + 1 # start from the next line
}
i2 = i2 + 1
}
if (i1 <= n) parse(text = piece) # must be an error there
x
}
# whether a code expression can be parsed
try_parse = function(code, silent = TRUE) {
!inherits(
try(parse(text = code, keep.source = FALSE), silent = silent), 'try-error'
)
}
# TODO: eventually remove the hack for R <= 3.2.2
parse_source = if (getRversion() > '3.2.2') function(lines) {
parse(text = lines, keep.source = TRUE)
} else function(lines) {
# adapted from evaluate
src = srcfilecopy('<text>', lines = '')
if (length(grep('\n', lines))) lines = unlist(strsplit(
sub('$', '\n', as.character(lines)), '\n'
))
src$lines = lines
parse(text = lines, srcfile = src)
}
# borrowed from knitr
# escape backslashes and {} for the alltt package
escape_latex = function(x) {
x = gsub('\\\\', '\\\\textbackslash', x)
x = gsub('([{}])', '\\\\\\1', x)
gsub('\\\\textbackslash', '\\\\textbackslash{}', x)
}
# escape special HTML chars
escape_html = function(x) {
x = gsub('&', '&', x)
x = gsub('<', '<', x)
x = gsub('>', '>', x)
x = gsub('"', '"', x)
x
}
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