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zutoml

zutoml reads TOML documents into ordinary R values and writes R values as TOML. Its parser and writer are written in C, with no system library and no runtime dependencies. Both pass every case of the toml-test conformance suite, for TOML 1.0.0 and 1.1.0.

  • Types come from the document. 2024-01-01 is a Date; "2024-01-01" is a string. zutoml never guesses from a string’s content.
  • Strict. An invalid document is refused, with the line and column at fault and a condition class you can catch. Size, depth, item and string limits bound untrusted input.
  • Deterministic output. The same R value gives the same bytes on every platform, and the text reads back.

Installation

Install zutoml from CRAN:

or the development version from GitHub:

# install.packages("pak")
pak::pak("pedrobtz/zutoml")

Example

Read a TOML file straight from a URL, here the pyproject.toml of pandas:

library(zutoml)

pyproject <- "https://raw.githubusercontent.com/pandas-dev/pandas/v3.0.6/pyproject.toml"

x <- toml_read(pyproject)
names(x)
#> [1] "build-system" "project"      "tool"
x$project$name
#> [1] "pandas"
x$project$`requires-python`
#> [1] ">=3.11"
x$project$dependencies
#> [1] "numpy>=1.26.0; python_version < '3.14'"
#> [2] "numpy>=2.3.3; python_version >= '3.14'"
#> [3] "python-dateutil>=2.8.2"
#> [4] "tzdata; sys_platform == 'win32'"
#> [5] "tzdata; sys_platform == 'emscripten'"

Read only the part you need with a path:

toml_read(pyproject, select = "project.optional-dependencies.excel")
#> [1] "odfpy>=1.4.1"           "openpyxl>=3.1.5"        "python-calamine>=0.3.0"
#> [4] "pyxlsb>=1.0.10"         "xlrd>=2.0.1"            "xlsxwriter>=3.2.0"

toml_read() also takes a file path or a connection, and toml_parse() a string. Write R values as TOML with toml_emit():

cat(toml_emit(list(name = "zutoml", version = 1L, tags = c("toml", "config"))))
#> name = "zutoml"
#> version = 1
#> tags = ["toml", "config"]

See vignette("zutoml") for a tour with pyproject.toml and Cargo.toml, and the usage guide for every task.