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use serde_yaml;
use serde_yaml::Value;
use std::collections::HashMap;
use std::error::Error;
pub use crate::Roadmap;
pub use crate::Status;
pub use crate::Step;
/// Result type for roadmap parsing.
type ParseResult<T> = Result<T, String>;
/// Create a new roadmap from a textual YAML representation.
pub fn from_yaml(yaml: &str) -> Result<Roadmap, Box<dyn Error>> {
let mut roadmap = Roadmap::new();
let map: HashMap<String, serde_yaml::Value> = serde_yaml::from_str(yaml)?;
for (name, value) in map {
let step = step_from_value(&name, &value)?;
roadmap.add_step(&step);
}
validate(&roadmap)?;
Ok(roadmap)
}
// Convert a Value into a Step, if possible.
fn step_from_value(name: &str, value: &Value) -> ParseResult<Step> {
match value {
Value::Mapping(_) => {
let label = parse_label(&value);
let status = parse_status(&value)?;
let mut step = Step::new(name, label);
step.set_status(status);
for depname in parse_depends(&value)?.iter() {
step.add_dependency(depname);
}
Ok(step)
}
_ => Err("step is not a mapping".to_string()),
}
}
// Get a sequence of depenencies.
fn parse_depends(map: &Value) -> ParseResult<Vec<&str>> {
let key_name = "depends";
let key = Value::String(key_name.to_string());
let mut depends: Vec<&str> = vec![];
let need_list_of_names = format!("'depends' must be a list of step names");
match map.get(&key) {
None => (),
Some(Value::Sequence(deps)) => {
for depname in deps.iter() {
match depname {
Value::String(depname) => depends.push(depname),
_ => return Err(need_list_of_names),
}
}
}
_ => return Err(need_list_of_names),
}
Ok(depends)
}
// Get label string from a Mapping element, or empty string.
fn parse_label(map: &Value) -> &str {
parse_string("label", map)
}
// Get status string from a Mapping element. Default to unknown status.
fn parse_status<'a>(map: &'a Value) -> ParseResult<Status> {
let text = parse_string("status", map);
match Status::from_text(text) {
Some(status) => Ok(status),
_ => Err(format!("unknown status: {:?}", text)),
}
}
// Get string value from a Mapping field, or empty string if field
// isn't there.
fn parse_string<'a>(key_name: &str, map: &'a Value) -> &'a str {
let key = Value::String(key_name.to_string());
match map.get(&key) {
Some(Value::String(s)) => s,
_ => "",
}
}
// Validate that the parsed, constructed roadmap is valid.
fn validate(roadmap: &Roadmap) -> ParseResult<()> {
// Is there exactly one goal?
match roadmap.count_goals() {
0 => return Err(format!("the roadmap doesn't have a goal")),
1 => (),
_ => return Err(format!("must have exactly one goal for roadmap")),
}
// Does every dependency exist?
for step in roadmap.iter() {
for depname in step.dependencies() {
match roadmap.get_step(depname) {
None => {
return Err(format!(
"step {} depends on missing {}",
step.name(),
depname
))
}
Some(_) => (),
}
}
}
Ok(())
}
#[cfg(test)]
mod tests {
use super::from_yaml;
#[test]
fn yaml_is_empty() {
let r = from_yaml("");
match r {
Ok(_) => panic!("expected a parse error"),
_ => (),
}
}
#[test]
fn yaml_is_list() {
let r = from_yaml("[]");
match r {
Ok(_) => panic!("expected a parse error"),
_ => (),
}
}
#[test]
fn yaml_map_entries_not_maps() {
let r = from_yaml("foo: []");
match r {
Ok(_) => panic!("expected a parse error"),
_ => (),
}
}
#[test]
fn yaml_unknown_dep() {
let r = from_yaml("foo: {depends: [bar]}");
match r {
Ok(_) => panic!("expected a parse error"),
_ => (),
}
}
#[test]
fn yaml_unknown_status() {
let r = from_yaml(r#"foo: {status: "bar"}"#);
match r {
Ok(_) => panic!("expected a parse error"),
_ => (),
}
}
#[test]
fn yaml_happy() {
let roadmap = from_yaml(
"
first:
label: the first step
second:
label: the second step
depends:
- first
",
)
.unwrap();
let names: Vec<&str> = roadmap.step_names().collect();
assert_eq!(names.len(), 2);
assert!(names.contains(&"first"));
assert!(names.contains(&"second"));
let first = roadmap.get_step("first").unwrap();
assert_eq!(first.name(), "first");
assert_eq!(first.label(), "the first step");
let deps: Vec<&String> = first.dependencies().collect();
assert_eq!(deps.len(), 0);
let second = roadmap.get_step("second").unwrap();
assert_eq!(second.name(), "second");
assert_eq!(second.label(), "the second step");
let deps: Vec<&String> = second.dependencies().collect();
assert_eq!(deps, vec!["first"]);
}
}
|
