Accept dependencies from pyproject.toml (#141)

Doesn't support extras yet. It's also supported for `pip uninstall`,
which `pip` itself doesn't support, but whatever.

Closes #127.

Cargo.lock

@@ -2028,9 +2028,11 @@ dependencies = [
  "puffin-package",
  "puffin-resolver",
  "puffin-workspace",
+ "pyproject-toml",
  "tempfile",
  "thiserror",
  "tokio",
+ "toml 0.8.2",
  "tracing",
  "tracing-subscriber",
  "tracing-tree",

crates/puffin-cli/Cargo.toml

@@ -33,9 +33,11 @@ indicatif = { workspace = true }
 itertools = { workspace = true }
 miette = { workspace = true, features = ["fancy"] }
 owo-colors = { workspace = true }
+pyproject-toml = { workspace = true }
 tempfile = { workspace = true }
 thiserror = { workspace = true }
 tokio = { workspace = true }
+toml = { workspace = true }
 tracing = { workspace = true }
 tracing-subscriber = { workspace = true }
 tracing-tree = { workspace = true }

crates/puffin-cli/src/requirements.rs

@@ -2,7 +2,7 @@ use std::path::PathBuf;
 use std::str::FromStr;
 
 use anyhow::{bail, Result};
-use itertools::Either;
+use fs_err as fs;
 
 use pep508_rs::Requirement;
 use puffin_package::requirements_txt::RequirementsTxt;
@@ -12,7 +12,9 @@ pub(crate) enum RequirementsSource {
     /// A dependency was provided on the command line (e.g., `pip install flask`).
     Name(String),
     /// Dependencies were provided via a `requirements.txt` file (e.g., `pip install -r requirements.txt`).
-    Path(PathBuf),
+    RequirementsTxt(PathBuf),
+    /// Dependencies were provided via a `pyproject.toml` file (e.g., `pip-compile pyproject.toml`).
+    PyprojectToml(PathBuf),
 }
 
 impl From<String> for RequirementsSource {
@@ -23,30 +25,56 @@ impl From<String> for RequirementsSource {
 
 impl From<PathBuf> for RequirementsSource {
     fn from(path: PathBuf) -> Self {
-        Self::Path(path)
+        if path.ends_with("pyproject.toml") {
+            Self::PyprojectToml(path)
+        } else {
+            Self::RequirementsTxt(path)
+        }
     }
 }
 
 impl RequirementsSource {
     /// Return an iterator over the requirements in this source.
     pub(crate) fn requirements(&self) -> Result<impl Iterator<Item = Requirement>> {
-        match self {
-            Self::Name(name) => {
-                let requirement = Requirement::from_str(name)?;
-                Ok(Either::Left(std::iter::once(requirement)))
+        let iter_name = if let Self::Name(name) = self {
+            let requirement = Requirement::from_str(name)?;
+            Some(std::iter::once(requirement))
+        } else {
+            None
+        };
+
+        let iter_requirements_txt = if let Self::RequirementsTxt(path) = self {
+            let requirements_txt = RequirementsTxt::parse(path, std::env::current_dir()?)?;
+            if !requirements_txt.constraints.is_empty() {
+                bail!("Constraints in requirements files are not supported");
             }
-            Self::Path(path) => {
-                let requirements_txt = RequirementsTxt::parse(path, std::env::current_dir()?)?;
-                if !requirements_txt.constraints.is_empty() {
-                    bail!("Constraints in requirements files are not supported");
-                }
-                Ok(Either::Right(
-                    requirements_txt
-                        .requirements
-                        .into_iter()
-                        .map(|entry| entry.requirement),
-                ))
-            }
-        }
+            Some(
+                requirements_txt
+                    .requirements
+                    .into_iter()
+                    .map(|entry| entry.requirement),
+            )
+        } else {
+            None
+        };
+
+        let iter_pyproject_toml = if let Self::PyprojectToml(path) = self {
+            let pyproject_toml =
+                toml::from_str::<pyproject_toml::PyProjectToml>(&fs::read_to_string(path)?)?;
+            Some(
+                pyproject_toml
+                    .project
+                    .into_iter()
+                    .flat_map(|project| project.dependencies.into_iter().flatten()),
+            )
+        } else {
+            None
+        };
+
+        Ok(iter_name
+            .into_iter()
+            .flatten()
+            .chain(iter_requirements_txt.into_iter().flatten())
+            .chain(iter_pyproject_toml.into_iter().flatten()))
     }
 }