[internal] Parse addresses using a generated parser

src/python/pants/build_graph/address.py

@@ -9,6 +9,10 @@
 from typing import Any, Sequence
 
 from pants.engine.engine_aware import EngineAwareParameter
+from pants.engine.internals import native_engine
+from pants.engine.internals.native_engine import (  # noqa: F401
+    AddressParseException as AddressParseException,
+)
 from pants.util.dirutil import fast_relpath, longest_dir_prefix
 from pants.util.strutil import strip_prefix
 
@@ -127,22 +131,7 @@ def prefix_subproject(spec_path: str) -> str:
                 return os.path.join(subproject, spec_path)
             return os.path.normpath(subproject)
 
-        spec_parts = spec.split(":", maxsplit=1)
-        path_component = spec_parts[0]
-        if len(spec_parts) == 1:
-            target_component = None
-            generated_parts = path_component.split("#", maxsplit=1)
-            if len(generated_parts) == 1:
-                generated_component = None
-            else:
-                path_component, generated_component = generated_parts
-        else:
-            generated_parts = spec_parts[1].split("#", maxsplit=1)
-            if len(generated_parts) == 1:
-                target_component = generated_parts[0]
-                generated_component = None
-            else:
-                target_component, generated_component = generated_parts
+        path_component, target_component, generated_component = native_engine.address_parse(spec)
 
         normalized_relative_to = None
         if relative_to:
@@ -324,18 +313,26 @@ def spec(self) -> str:
         :API: public
         """
         prefix = "//" if not self.spec_path else ""
-        if self._relative_file_path is not None:
-            file_portion = f"{prefix}{self.filename}"
+        if self._relative_file_path is None:
+            path = self.spec_path
+            target = "" if self._target_name is None and self.generated_name else self.target_name
+        else:
+            path = self.filename
             parent_prefix = "../" * self._relative_file_path.count(os.path.sep)
-            return (
-                file_portion
+            target = (
+                ""
                 if self._target_name is None and not parent_prefix
-                else f"{file_portion}:{parent_prefix}{self.target_name}"
+                else f"{parent_prefix}{self.target_name}"
             )
-        if self.generated_name is not None:
-            target_portion = f":{self._target_name}" if self._target_name is not None else ""
-            return f"{prefix}{self.spec_path}{target_portion}#{self.generated_name}"
-        return f"{prefix}{self.spec_path}:{self.target_name}"
+        target_sep = ":" if target else ""
+        if self.generated_name is None:
+            generated_sep = ""
+            generated = ""
+        else:
+            generated_sep = "#"
+            generated = self.generated_name
+
+        return f"{prefix}{path}{target_sep}{target}{generated_sep}{generated}"
 
     @property
     def path_safe_spec(self) -> str:
@@ -345,18 +342,19 @@ def path_safe_spec(self) -> str:
         if self._relative_file_path:
             parent_count = self._relative_file_path.count(os.path.sep)
             parent_prefix = "@" * parent_count if parent_count else "."
-            file_portion = f".{self._relative_file_path.replace(os.path.sep, '.')}"
+            path = f".{self._relative_file_path.replace(os.path.sep, '.')}"
         else:
             parent_prefix = "."
-            file_portion = ""
+            path = ""
         if parent_prefix == ".":
-            target_portion = f"{parent_prefix}{self._target_name}" if self._target_name else ""
+            target = f"{parent_prefix}{self._target_name}" if self._target_name else ""
         else:
-            target_portion = f"{parent_prefix}{self.target_name}"
-        generated_portion = (
+            target = f"{parent_prefix}{self.target_name}"
+        generated = (
             f"@{self.generated_name.replace(os.path.sep, '.')}" if self.generated_name else ""
         )
-        return f"{self.spec_path.replace(os.path.sep, '.')}{file_portion}{target_portion}{generated_portion}"
+        prefix = self.spec_path.replace(os.path.sep, ".")
+        return f"{prefix}{path}{target}{generated}"
 
     def maybe_convert_to_target_generator(self) -> Address:
         """If this address is generated, convert it to its generator target.

src/python/pants/build_graph/address_test.py

@@ -5,7 +5,13 @@
 
 import pytest
 
-from pants.build_graph.address import Address, AddressInput, InvalidSpecPath, InvalidTargetName
+from pants.build_graph.address import (
+    Address,
+    AddressInput,
+    AddressParseException,
+    InvalidSpecPath,
+    InvalidTargetName,
+)
 
 
 def test_address_input_parse_spec() -> None:
@@ -90,15 +96,26 @@ def test_address_input_parse_bad_path_component(spec: str) -> None:
         AddressInput.parse(spec)
 
 
+@pytest.mark.parametrize(
+    "spec,expected",
+    [
+        ("a:", "non-empty target name"),
+        ("//:", "non-empty target name"),
+        ("//:@t", "non-empty target name"),
+    ],
+)
+def test_address_input_parse(spec: str, expected: str) -> None:
+    with pytest.raises(AddressParseException) as e:
+        AddressInput.parse(spec)
+    assert expected in str(e.value)
+
+
 @pytest.mark.parametrize(
     "spec",
     [
         "",
-        "a:",
         "a::",
         "//",
-        "//:",
-        "//:@t",
         "//:!t",
         "//:?",
         "//:=",

src/python/pants/engine/internals/native_engine.pyi

@@ -17,6 +17,15 @@ from pants.engine.process import InteractiveProcessResult
 #   see https://github.com/psf/black/issues/1548
 # flake8: noqa: E302
 
+# ------------------------------------------------------------------------------
+# Address (parsing)
+# ------------------------------------------------------------------------------
+
+class AddressParseException(Exception):
+    pass
+
+def address_parse(spec: str) -> tuple[str, str | None, str | None]: ...
+
 # ------------------------------------------------------------------------------
 # Scheduler
 # ------------------------------------------------------------------------------

src/rust/engine/Cargo.toml

@@ -20,6 +20,7 @@ resolver = "2"
 # (e.g. fs_util) won't be included when we build/test things.
 members = [
   ".",
+  "address",
   "async_latch",
   "async_value",
   "cache",
@@ -60,6 +61,7 @@ members = [
 # On Ubuntu, that means installing libfuse-dev. On OSX, that means installing OSXFUSE.
 default-members = [
   ".",
+  "address",
   "async_latch",
   "async_value",
   "cache",
@@ -102,6 +104,7 @@ extension-module = ["pyo3/extension-module"]
 default = []
 
 [dependencies]
+address = { path = "address" }
 async_latch = { path = "async_latch" }
 # Pin async-trait due to https://github.com/dtolnay/async-trait/issues/144.
 async-trait = "=0.1.42"

src/rust/engine/address/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+version = "0.0.1"
+edition = "2021"
+name = "address"
+authors = [ "Pants Build <pantsbuild@gmail.com>" ]
+publish = false
+
+[dependencies]
+peg = "0.7"

src/rust/engine/address/src/lib.rs

@@ -0,0 +1,66 @@
+// Copyright 2021 Pants project contributors (see CONTRIBUTORS.md).
+// Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+#![deny(warnings)]
+// Enable all clippy lints except for many of the pedantic ones. It's a shame this needs to be copied and pasted across crates, but there doesn't appear to be a way to include inner attributes from a common source.
+#![deny(
+  clippy::all,
+  clippy::default_trait_access,
+  clippy::expl_impl_clone_on_copy,
+  clippy::if_not_else,
+  clippy::needless_continue,
+  clippy::unseparated_literal_suffix,
+  clippy::used_underscore_binding
+)]
+// It is often more clear to show that nothing is being moved.
+#![allow(clippy::match_ref_pats)]
+// Subjective style.
+#![allow(
+  clippy::len_without_is_empty,
+  clippy::redundant_field_names,
+  clippy::too_many_arguments
+)]
+// Default isn't as big a deal as people seem to think it is.
+#![allow(clippy::new_without_default, clippy::new_ret_no_self)]
+// Arc<Mutex> can be more clear than needing to grok Orderings:
+#![allow(clippy::mutex_atomic)]
+
+pub struct AddressInput<'a> {
+  pub path: &'a str,
+  pub target: Option<&'a str>,
+  pub generated: Option<&'a str>,
+}
+
+peg::parser! {
+    grammar relative_address_parser() for str {
+        rule path() -> &'input str = s:$([^':' | '#']*) {s}
+
+        rule target_name() -> &'input str
+            = quiet!{ s:$([^'#' | '@']+) { s } }
+            / expected!("a non-empty target name to follow a `:`.")
+
+        rule target() -> &'input str = ":" s:target_name() { s }
+
+        rule generated_name() -> &'input str
+            = quiet!{ s:$([_]+) { s } }
+            / expected!("a non-empty generated target name to follow a `#`.")
+
+        rule generated() -> &'input str = "#" s:generated_name() { s }
+
+        pub(crate) rule relative_address() -> AddressInput<'input>
+            = path:path() target:target()? generated:generated()? {
+                AddressInput {
+                    path,
+                    target,
+                    generated,
+                }
+            }
+    }
+}
+
+pub fn parse_address(value: &str) -> Result<AddressInput, String> {
+  let relative_address = relative_address_parser::relative_address(value)
+    .map_err(|e| format!("Failed to parse Address `{value}`: {e}"))?;
+
+  Ok(relative_address)
+}

src/rust/engine/src/externs/address.rs

@@ -0,0 +1,30 @@
+// Copyright 2022 Pants project contributors (see CONTRIBUTORS.md).
+// Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+use pyo3::create_exception;
+use pyo3::exceptions::PyException;
+use pyo3::prelude::*;
+
+use address::parse_address;
+
+create_exception!(native_engine, AddressParseException, PyException);
+
+pub fn register(py: Python, m: &PyModule) -> PyResult<()> {
+  m.add(
+    "AddressParseException",
+    py.get_type::<AddressParseException>(),
+  )?;
+  m.add_function(wrap_pyfunction!(address_parse, m)?)?;
+  Ok(())
+}
+
+/// Parses an Address spec into:
+/// 1. a path component
+/// 2. a target component
+/// 3. a generated component
+///
+#[pyfunction]
+fn address_parse(spec: &str) -> PyResult<(&str, Option<&str>, Option<&str>)> {
+  let address = parse_address(spec).map_err(AddressParseException::new_err)?;
+  Ok((address.path, address.target, address.generated))
+}

src/rust/engine/src/externs/interface.rs

@@ -53,6 +53,7 @@ use crate::{
 
 #[pymodule]
 fn native_engine(py: Python, m: &PyModule) -> PyO3Result<()> {
+  externs::address::register(py, m)?;
   externs::fs::register(m)?;
   externs::nailgun::register(py, m)?;
   externs::scheduler::register(m)?;

src/rust/engine/src/externs/mod.rs

@@ -20,6 +20,7 @@ use logging::PythonLogLevel;
 use crate::interning::Interns;
 use crate::python::{Failure, Key, TypeId, Value};
 
+mod address;
 pub mod engine_aware;
 pub mod fs;
 mod interface;