feat: add support for json config files (#55)

* feat: add support for json config files

* feat: make json the preferred config format

* feat: allow yaml config format

* feat!: remove compatibility tweaks for tt07's config.tcl

---------

Co-authored-by: htfab <mpw@htamas.net>

config_utils.py

@@ -0,0 +1,102 @@
+import json
+import logging
+import os
+import re
+import tkinter
+from collections.abc import Iterable
+
+import yaml
+
+
+class ConfigFileError(Exception):
+    pass
+
+
+def read_tcl_config(file: str, design_dir: str | None = None):
+    logging.warning(
+        "Support for TCL configuration files is deprecated and will be removed"
+    )
+    if design_dir is None:
+        design_dir = os.path.dirname(file)
+    design_dir = os.path.realpath(design_dir)
+    tcl_code = open(file).read()
+    interp = tkinter.Tcl()
+    interp.eval("array unset ::env")
+    interp.setvar("env(DESIGN_DIR)", design_dir)
+    config = {}
+    env_rx = re.compile(r"(?:\:\:)?env\((\w+)\)")
+
+    def py_set(key: str, value: str | None = None):
+        if match := env_rx.fullmatch(key):
+            if value is not None:
+                value = value.replace(design_dir, "dir::")
+                value = value.replace("dir::/", "dir::")
+                config[match.group(1)] = value
+
+    py_set_name = interp.register(py_set)
+    interp.call("rename", py_set_name, "_py_set")
+    interp.call("rename", "set", "_orig_set")
+    interp.eval("proc set args { _py_set {*}$args; tailcall _orig_set {*}$args; }")
+    interp.eval(tcl_code)
+    return config
+
+
+def read_json_config(file: str):
+    return json.load(open(file))
+
+
+def read_yaml_config(file: str):
+    return yaml.safe_load(open(file))
+
+
+def read_config(basename: str, formats: Iterable[str], design_dir: str | None = None):
+    for fmt in formats:
+        file = f"{basename}.{fmt}"
+        if os.path.exists(file):
+            if fmt == "tcl":
+                return read_tcl_config(file, design_dir)
+            elif fmt == "json":
+                return read_json_config(file)
+            elif fmt == "yaml":
+                return read_yaml_config(file)
+            else:
+                raise ConfigFileError(f"Unexpected configuration file format: {fmt}")
+    raise ConfigFileError(
+        f"Could not file configuration file {basename}.{{{'|'.join(formats)}}}"
+    )
+
+
+def write_tcl_config(config: dict, file: str):
+    logging.warning(
+        "Support for TCL configuration files is deprecated and will be removed"
+    )
+    with open(file, "w") as f:
+        for key, value in config.items():
+            if type(value) in (list, tuple):
+                value = " ".join(value)
+            if type(value) == str:
+                value = value.replace("dir::", "$::env(DESIGN_DIR)/")
+            print(f'set ::env({key}) "{value}"', file=f)
+
+
+def write_json_config(config: dict, file: str):
+    with open(file, "w") as f:
+        json.dump(config, f, indent=2)
+
+
+def write_yaml_config(config: dict, file: str):
+    with open(file, "w") as f:
+        yaml.safe_dump(config, f, default_flow_style=False, sort_keys=False)
+
+
+def write_config(config: dict, basename: str, formats: Iterable[str]):
+    for fmt in formats:
+        file = f"{basename}.{fmt}"
+        if fmt == "tcl":
+            write_tcl_config(config, file)
+        elif fmt == "json":
+            write_json_config(config, file)
+        elif fmt == "yaml":
+            write_yaml_config(config, file)
+        else:
+            raise ConfigFileError("Unexpected configuration file format: {fmt}")