chore: Do not allocate a vector in parser::parse

Author: Stranger6667

src/bin/parsereqs.rs

@@ -1,5 +1,5 @@
 use globwalk::GlobError;
-use requirements::{self, Requirement};
+use requirements::{self, parse};
 use std::{env, fs, path::Path};
 use walkdir::DirEntry;
 
@@ -17,16 +17,14 @@ fn main() {
 
 fn parse_requirements(path: &Path) {
     let content = fs::read_to_string(&path).expect("Cannot read file");
-    let requirement_file: Vec<Requirement> = requirements::parse_str(&content).unwrap();
-
-    for requirement in requirement_file.into_iter() {
+    for requirement in parse(&content).unwrap() {
         if let Some(name) = requirement.name {
             print!("{} ", name);
         }
         if let Some(comment) = requirement.comment {
             print!("({}) ", comment)
         }
-        for (comparison, version) in requirement.specs.into_iter() {
+        for (comparison, version) in &requirement.specs {
             print!("{}{} ", comparison, version);
         }
         println!();

src/lib.rs

@@ -24,12 +24,12 @@ mod parser;
 pub mod enums;
 mod requirements;
 
-use parser::parse;
+pub use parser::parse;
 pub use crate::requirements::Requirement;
 
 /// Parses requirements from a string
 pub fn parse_str(content: &str) -> Result<Vec<Requirement>, String> {
-    parse(content)
+    Ok(parse(content).map(Iterator::collect)?)
 }
 
 // TODO: Add file loading code (recursive?) here.

src/parser/mod.rs

@@ -76,18 +76,15 @@ fn parse_package(parsed: Pair<'_, Rule>) -> Requirement<'_> {
     package
 }
 
-pub fn parse(unparsed_file: &str) -> Result<Vec<Requirement>, String> {
+pub fn parse(unparsed_file: &str) -> Result<impl Iterator<Item = Requirement>, String> {
     let req_file = match RequirementParser::parse(Rule::requirement_file, unparsed_file) {
         Ok(mut rules) => rules.next().unwrap(),
         Err(_) => return Err(String::from("Failed to parse requirements"))
     };
 
-    let requirements: Vec<Requirement> = req_file
+    Ok(req_file
         .into_inner()
         .filter(|pair| pair.as_rule() == Rule::line)
-        .map(parse_package)
-        .collect();
-
-    Ok(requirements)
+        .map(parse_package))
 }