yaml12 (version 0.1.0)

parse_yaml: Parse YAML 1.2 document(s) into base R structures.

Description

parse_yaml() takes strings of YAML; read_yaml() reads from a file path.

Usage

parse_yaml(text, multi = FALSE, simplify = TRUE, handlers = NULL)
read_yaml(path, multi = FALSE, simplify = TRUE, handlers = NULL)

Value

When multi = FALSE, returns a parsed R object for the first document. When multi = TRUE, returns a list of parsed documents.

Arguments

text

Character vector; elements are concatenated with "\n".

multi

When TRUE, return a list containing all documents in the stream.

simplify

When FALSE, keep YAML sequences as R lists instead of simplifying to atomic vectors.

handlers

Named list of R functions with names corresponding to YAML tags; matching handlers transform tagged values.

path

Scalar string path to a YAML file`.

Details

YAML tags without a corresponding handler are preserved in a yaml_tag attribute. Mappings with keys that are not all simple scalar strings are returned as a named list with a yaml_keys attribute.

Examples

dput(parse_yaml("foo: [1, 2, 3]"))

# homogeneous sequences simplify by default.
# YAML null maps to NA in otherwise homogeneous sequences.
dput(parse_yaml("foo: [1, 2, 3, null]"))

# mixed type sequence never simplify
dput(parse_yaml("[1, true, cat]"))

# use `simplify=FALSE` to always return sequences as lists.
str(parse_yaml("foo: [1, 2, 3, null]", simplify = FALSE))

# Parse multiple documents when requested.
stream <- "
---
first: 1
---
second: 2
"
str(parse_yaml(stream, multi = TRUE))

# Read from a file; keep sequences as lists.
path <- tempfile(fileext = ".yaml")
writeLines("alpha: [true, null]\nbeta: 3.5", path)
str(read_yaml(path, simplify = FALSE))