feat(config)!: Add enviroment variables interpolation for env_{KEY}

docs/config-v3-documentation.md

@@ -659,11 +659,13 @@ upon errors is inherently unreliable.
 <!-- md:version 2.1.0 -->
 <!-- md:type string -->
 <!-- md:default-empty -->
-<!-- md:flag experimental -->
 
-Sets an environment variable when running this program.
+Sets an environment variable when running this program. You can use `${...}` interpolation for substituting environment variables.
 
-For example `env_DEBUG=true` sets `DEBUG` to have value `true`.
+??? example "`env_{KEY}` usage"
+    For example `env_DEBUG=true` sets `DEBUG` to have value `true`.
+
+    When running pisek with `TASK` set to `aplusb`, `env_DATASET=../{TASK}` produces `DATASET=../aplusb`. (However, the program will have no access to `TASK` by default.)
 
 ## [build]
 Sections describing how to build a program.

fixtures/max/config

@@ -59,6 +59,9 @@ tests=@all
 [solution_solve_java_complex]
 tests=@all
 
+[solution_solve_env]
+tests=@all
+
 [run_solution]
 time_limit=0.2
 
@@ -84,6 +87,10 @@ exec=min
 build=solve_rs_complex
 exec=max
 
+[run_solution:solve_env]
+env_TASK=max
+env_DBG=${DEBUG}_${DEBUG}
+
 [build_gen:gen]
 sources=gen/gen gen/random
 

fixtures/max/solve_env.py

@@ -0,0 +1,8 @@
+#!/usr/bin/env python3
+import os
+
+assert os.environ["TASK"] == "max"
+assert os.environ["DBG"] == "false_false"
+
+input()
+print(max(map(int, input().split())))

pisek/config/task_config.py

@@ -701,6 +701,53 @@ def load_dict(
     def validate_name(cls, value: str) -> str:
         return _validate_program_name("program name", value)
 
+    @field_validator("env", mode="before")
+    def interpolate_env(cls, dictionary: dict[str, str]) -> dict[str, str]:
+        def raise_err(error_type: str, message: str, key: str):
+            raise PydanticCustomError(
+                error_type, message, {"_loc": key, f"env_{key}": dictionary[key]}
+            )
+
+        def interpolate(key: str, val: str) -> str:
+            state: list[str] = [""]
+            i = 0
+            while i < len(val):
+                char = val[i]
+                if char == "\\":
+                    if i == len(val) - 1:
+                        raise_err("env_wrong_escape", "Unterminated escape", key)
+                    i += 1
+                    state[-1] += val[i]
+                elif val[i : i + 2] == "${":
+                    state.append("")
+                    i += 1
+                elif char == "}" and len(state) > 1:
+                    var_name = state.pop()
+                    if var_name not in os.environ:
+                        raise_err(
+                            "unknown_variable",
+                            f"No environment variable '{var_name}'",
+                            key,
+                        )
+                    state[-1] += os.environ[var_name]
+                elif char in "${}":
+                    raise_err("unescaped_char", f"Unescaped character '{char}'", key)
+                else:
+                    state[-1] += char
+
+                i += 1
+
+            if len(state) > 1:
+                raise_err(
+                    "env_unterminated_interpolation", "Unterminated interpolation", key
+                )
+
+            return state[0]
+
+        for key in dictionary:
+            dictionary[key] = interpolate(key, dictionary[key])
+        return dictionary
+
 
 class BuildSection(BaseEnv):
     program_names: ClassVar[dict[str, str]] = {}
@@ -902,7 +949,9 @@ def _format_message(err: ErrorDetails) -> str:
         if ctx == {}:
             return f"{err['msg']}."
         return f"{err['msg']}:\n" + tab(
-            "\n".join(f"{key}={val}" for key, val in ctx.items())
+            "\n".join(
+                f"{key}={val}" for key, val in ctx.items() if not key.startswith("_")
+            )
         )
     return f"{err['msg']}: '{inp}'"
 
@@ -914,12 +963,12 @@ def _convert_errors(e: ValidationError, config_values: ConfigValuesDict) -> list
         for loc in error["loc"]:
             value = value[loc]
 
-        if not isinstance(value, ConfigValue):
-            location = (
-                value["_section"].location() if "_section" in value else "global config"
-            )
-        else:
+        if isinstance(value, ConfigValue):
             location = value.location()
+        elif "_section" in value:
+            location = value["_section"].location()
+        else:
+            location = value[error["ctx"]["_loc"]].location()
 
         error_msgs.append(f"In {location}:\n" + tab(_format_message(error)))
     return error_msgs

tests/test_max.py

@@ -1,3 +1,4 @@
+import os
 import unittest
 
 from util import TestFixtureVariant
@@ -8,6 +9,9 @@ class TestMax(TestFixtureVariant):
     def fixture_path(self) -> str:
         return "fixtures/max/"
 
+    def set_env(self):
+        os.environ["DEBUG"] = "false"
+
 
 if __name__ == "__main__":
     unittest.main(verbosity=2)

tests/util.py

@@ -19,6 +19,9 @@ class TestFixture(unittest.TestCase):
     def fixture_path(self) -> str | None:
         return None
 
+    def set_env(self) -> None:
+        pass
+
     def setUp(self) -> None:
         os.environ["LOG_LEVEL"] = "debug"
 
@@ -49,6 +52,8 @@ def setUp(self) -> None:
                 os.path.join(self.fixtures_dir, "pisek"),
             )
 
+        self.set_env()
+
         assert_task_dir(
             self.task_dir,
             os.environ.get("PISEK_DIRECTORY"),
@@ -123,6 +128,7 @@ def runTest(self) -> None:
         if not self.fixture_path:
             return
 
+        self.set_env()
         self.modify_task()
         self.log_files()