xml_parse_data: Convert R parse data to XML

Description

In recent R versions the parser can attach source code location information to the parsed expressions. This information is often useful for static analysis, e.g. code linting. It can be accessed via the getParseData function.

Usage

xml_parse_data(x, includeText = NA, pretty = FALSE)

Arguments

an expression returned from parse, or a function or other object with source reference information

includeText

logical; whether to include the text of parsed items in the result

pretty

Whether to pretty-indent the XML output. It has a small overhead which probably only matters for very large source files.

Value

An XML string representing the parse data. See details below.

Details

xml_parse_data converts this information to an XML tree. The R parser's token names are preserved in the XML as much as possible, but some of them are not valid XML tag names, so they are renamed, see the xml_parse_token_map vector for the mapping.

The top XML tag is <exprlist>, which is a list of expressions, each expression is an <expr> tag. Each tag has attributes that define the location: line1, col1, line2, col2. These are from the getParseData data frame column names.

See an example below. See also the README at https://github.com/r-lib/xmlparsedata#readme for examples on how to search the XML tree with the xml2 package and XPath expressions.

Note that `xml_parse_data()` silently drops all control characters (0x01-0x1f) from the input, except horizontal tab (0x09) and newline (0x0a), because they are invalid in XML 1.0.

Examples

Run this code

# NOT RUN {
code <- "function(a = 1, b = 2) {\n  a + b\n}\n"
expr <- parse(text = code, keep.source = TRUE)

# The base R way:
getParseData(expr)

cat(xml_parse_data(expr, pretty = TRUE))
# }