Add explicit index support

Author: charliermarsh

Cargo.lock

@@ -0,0 +1,146 @@
+use crate::{IndexUrl, IndexUrlError};
+use std::str::FromStr;
+use thiserror::Error;
+use url::Url;
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct Index {
+    /// The name of the index.
+    ///
+    /// Index names can be used to reference indexes elsewhere in the configuration. For example,
+    /// you can pin a package to a specific index by name:
+    ///
+    /// ```toml
+    /// [[tool.uv.index]]
+    /// name = "pytorch"
+    /// url = "https://download.pytorch.org/whl/cu121"
+    ///
+    /// [tool.uv.sources]
+    /// torch = { index = "pytorch" }
+    /// ```
+    pub name: Option<String>,
+    /// The URL of the index.
+    ///
+    /// Expects to receive a URL (e.g., `https://pypi.org/simple`) or a local path.
+    pub url: IndexUrl,
+    /// Mark the index as explicit.
+    ///
+    /// Explicit indexes will _only_ be used when explicitly enabled via a `[tool.uv.sources]`
+    /// definition, as in:
+    ///
+    /// ```toml
+    /// [[tool.uv.index]]
+    /// name = "pytorch"
+    /// url = "https://download.pytorch.org/whl/cu121"
+    /// explicit = true
+    ///
+    /// [tool.uv.sources]
+    /// torch = { index = "pytorch" }
+    /// ```
+    #[serde(default)]
+    pub explicit: bool,
+    /// Mark the index as the default index.
+    ///
+    /// By default, uv uses PyPI as the default index, such that even if additional indexes are
+    /// defined via `[[tool.uv.index]]`, PyPI will still be used as a fallback for packages that
+    /// aren't found elsewhere. To disable the PyPI default, set `default = true` on at least one
+    /// other index.
+    ///
+    /// Marking an index as default will move it to the front of the list of indexes, such that it
+    /// is given the highest priority when resolving packages.
+    #[serde(default)]
+    pub default: bool,
+    // /// The type of the index.
+    // ///
+    // /// Indexes can either be PEP 503-compliant (i.e., a registry implementing the Simple API) or
+    // /// structured as a flat list of distributions (e.g., `--find-links`). In both cases, indexes
+    // /// can point to either local or remote resources.
+    // #[serde(default)]
+    // pub r#type: IndexKind,
+}
+
+// #[derive(
+//     Default, Debug, Copy, Clone, Hash, Eq, PartialEq, serde::Serialize, serde::Deserialize,
+// )]
+// #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+// pub enum IndexKind {
+//     /// A PEP 503 and/or PEP 691-compliant index.
+//     #[default]
+//     Simple,
+//     /// An index containing a list of links to distributions (e.g., `--find-links`).
+//     Flat,
+// }
+
+impl Index {
+    /// Initialize an [`Index`] from a pip-style `--index-url`.
+    pub fn from_index_url(url: IndexUrl) -> Self {
+        Self {
+            url,
+            name: None,
+            explicit: false,
+            default: true,
+        }
+    }
+
+    /// Initialize an [`Index`] from a pip-style `--extra-index-url`.
+    pub fn from_extra_index_url(url: IndexUrl) -> Self {
+        Self {
+            url,
+            name: None,
+            explicit: false,
+            default: false,
+        }
+    }
+
+    /// Return the [`IndexUrl`] of the index.
+    pub fn url(&self) -> &IndexUrl {
+        &self.url
+    }
+
+    /// Return the raw [`URL`] of the index.
+    pub fn raw_url(&self) -> &Url {
+        self.url.url()
+    }
+}
+
+impl FromStr for Index {
+    type Err = IndexSourceError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        // Determine whether the source is prefixed with a name, as in `name=https://pypi.org/simple`.
+        if let Some((name, url)) = s.split_once('=') {
+            if name.is_empty() {
+                return Err(IndexSourceError::EmptyName);
+            }
+
+            if name.chars().all(char::is_alphanumeric) {
+                let url = IndexUrl::from_str(url)?;
+                return Ok(Self {
+                    name: Some(name.to_string()),
+                    url,
+                    explicit: false,
+                    default: false,
+                });
+            }
+        }
+
+        // Otherwise, assume the source is a URL.
+        let url = IndexUrl::from_str(s)?;
+        Ok(Self {
+            name: None,
+            url,
+            explicit: false,
+            default: false,
+        })
+    }
+}
+
+/// An error that can occur when parsing an [`Index`].
+#[derive(Error, Debug)]
+pub enum IndexSourceError {
+    #[error(transparent)]
+    Url(#[from] IndexUrlError),
+    #[error("Index included a name, but the name was empty")]
+    EmptyName,
+}