"""
:Description: Provides a class that takes text from a Jinja-formatted recipe file and parses it. This allows for easy
semantic understanding and manipulation of the file.
For historical reasons, this is called the `parser` even though it provides editing capabilities.
Initially the `RecipeParser` class and `RecipeReader` class were one massive class.
Patching these files is done using a JSON-patch like syntax. This project closely conforms to the
RFC 6902 spec, but deviates in some specific ways to handle the Jinja variables and comments found in
conda recipe files.
Links:
- https://jsonpatch.com/
- https://datatracker.ietf.org/doc/html/rfc6902/
"""
from __future__ import annotations
import difflib
import re
from typing import Final, Optional, TypeGuard, cast
from jsonschema import validate as schema_validate
from conda_recipe_manager.parser._node import Node
from conda_recipe_manager.parser._traverse import (
INVALID_IDX,
remap_child_indices_virt_to_phys,
traverse,
traverse_with_index,
)
from conda_recipe_manager.parser._types import Regex, StrStack
from conda_recipe_manager.parser._utils import str_to_stack_path
from conda_recipe_manager.parser.enums import SelectorConflictMode
from conda_recipe_manager.parser.exceptions import JsonPatchValidationException
from conda_recipe_manager.parser.recipe_reader import RecipeReader
from conda_recipe_manager.parser.types import JSON_PATCH_SCHEMA
from conda_recipe_manager.types import PRIMITIVES_TUPLE, JsonPatchType, JsonType
[docs]
class RecipeParser(RecipeReader):
"""
Class that parses a recipe file string and provides editing tools for changing values in the document.
"""
# Static set of patch operations that require `from`. The others require `value` or nothing.
_patch_ops_requiring_from = set(["copy", "move"])
## JINJA Variable Editing Functions ##
[docs]
def set_variable(self, var: str, value: JsonType) -> None:
"""
Adds or changes an existing Jinja variable.
:param var: Variable to modify
:param value: Value to set
"""
self._vars_tbl[var] = value
self._is_modified = True
[docs]
def del_variable(self, var: str) -> None:
"""
Remove a variable from the project. If one is not found, no changes are made.
:param var: Variable to delete
"""
if not var in self._vars_tbl:
return
del self._vars_tbl[var]
self._is_modified = True
## Selector Editing Functions ##
[docs]
def add_selector(self, path: str, selector: str, mode: SelectorConflictMode = SelectorConflictMode.REPLACE) -> None:
"""
Given a path, add a selector (include the surrounding brackets) to the line denoted by path.
:param path: Path to add a selector to
:param selector: Selector statement to add
:param mode: (Optional) Indicates how to handle a conflict if a selector already exists at this path.
:raises KeyError: If the path provided is not found
:raises ValueError: If the selector provided is malformed
"""
path_stack = str_to_stack_path(path)
node = traverse(self._root, path_stack)
if node is None:
raise KeyError(f"Path not found: {path!r}")
if not Regex.SELECTOR.match(selector):
raise ValueError(f"Invalid selector provided: {selector}")
# Helper function that extracts the outer set of []'s in a selector
def _extract_selector(s: str) -> str:
return s.replace("[", "", 1)[::-1].replace("]", "", 1)[::-1]
comment = ""
old_selector_found = Regex.SELECTOR.search(node.comment)
if node.comment == "" or mode == SelectorConflictMode.REPLACE:
comment = f"# {selector}"
# "Append" to existing selectors
elif old_selector_found:
logic_op = "and" if mode == SelectorConflictMode.AND else "or"
old_selector = _extract_selector(old_selector_found.group())
new_selector = _extract_selector(selector)
comment = f"# [{old_selector} {logic_op} {new_selector}]"
# If the comment is not a selector, put the selector first, then append the comment.
else:
# Strip the existing comment of it's leading `#` symbol
comment = f"# {selector} " + node.comment.replace("#", "", 1).strip()
node.comment = comment
# Some lines of YAML correspond to multiple nodes. For consistency, we need to ensure that comments are
# duplicate across all nodes on a line.
if node.is_single_key():
node.children[0].comment = comment
self._rebuild_selectors()
self._is_modified = True
[docs]
def remove_selector(self, path: str) -> Optional[str]:
"""
Given a path, remove a selector to the line denoted by path.
- If a selector does not exist, nothing happens.
- If a comment exists after the selector, keep it, discard the selector.
:param path: Path to add a selector to
:raises KeyError: If the path provided is not found
:returns: If found, the selector removed (includes surrounding brackets). Otherwise, returns None
"""
path_stack = str_to_stack_path(path)
node = traverse(self._root, path_stack)
if node is None:
raise KeyError(f"Path not found: {path!r}")
search_results = Regex.SELECTOR.search(node.comment)
if not search_results:
return None
selector = search_results.group(0)
comment = node.comment.replace(selector, "")
# Sanitize potential edge-case scenarios after a removal
comment = comment.replace("# ", "# ").replace("# # ", "# ")
# Detect and remove empty comments. Other comments should remain intact.
if comment.strip() == "#":
comment = ""
node.comment = comment
# Some lines of YAML correspond to multiple nodes. For consistency, we need to ensure that comments are
# duplicate across all nodes on a line.
if node.is_single_key():
node.children[0].comment = comment
self._rebuild_selectors()
self._is_modified = True
return selector
## Comment Editing Functions ##
## YAML Patching Functions ##
@staticmethod
def _is_valid_patch_node(node: Optional[Node], node_idx: int) -> TypeGuard[Node]:
"""
Indicates if the target node to perform a patch operation against is a valid node. This is based on the RFC spec
for JSON patching paths.
:param node: Target node to validate
:param node_idx: If the caller is evaluating that a list member, exists, this is the VIRTUAL index into that
list. Otherwise this value should be less than 0.
:returns: True if the node can be patched. False otherwise.
"""
# Path not found
if node is None:
return False
# Leaf nodes contain values and not path information. Paths should not be made that access leaf nodes, with the
# exception of members of a list and keys. Making such a path violates the RFC.
if not node.list_member_flag and not node.key_flag and node.is_leaf():
return False
if node_idx >= 0:
# Check the bounds if the target requires the use of an index, remembering to use the virtual look-up table.
idx_map = remap_child_indices_virt_to_phys(node.children)
if node_idx < 0 or node_idx > (len(idx_map) - 1):
return False
# You cannot use the list access feature to access non-lists
if len(node.children) and not node.children[idx_map[node_idx]].list_member_flag:
return False
return True
def _patch_add_find_target(self, path_stack: StrStack) -> tuple[Optional[Node], int, int, str, bool]:
"""
Finds the target node of an `add()` operation, along with some supporting information.
This function does not modify the parse tree.
:param path_stack: Path that describes a location in the tree, as a list, treated like a stack.
:returns: A tuple containing: - The target node, if found (or the parent node if the target is a list member) -
The index of a node if the target is a list member - An additional path that needs to be created, if
applicable - A flag indicating if the new data will be appended to a list
"""
if len(path_stack) == 0:
return None, INVALID_IDX, INVALID_IDX, "", False
# Special case that only applies to `add`. The `-` character indicates the new element can be added to the end
# of the list.
append_to_list = False
if path_stack[0] == "-":
path_stack.pop(0)
append_to_list = True
path_stack_copy = path_stack.copy()
node, virt_idx, phys_idx = traverse_with_index(self._root, path_stack)
# Attempt to run a second time, if no node is found. As per the RFC, the containing object/list must exist. That
# allows us to create only 1 level in the path.
path_to_create = ""
if node is None:
path_to_create = path_stack_copy.pop(0)
node, virt_idx, phys_idx = traverse_with_index(self._root, path_stack_copy)
return node, virt_idx, phys_idx, path_to_create, append_to_list
def _patch_add(self, path_stack: StrStack, value: JsonType) -> bool:
"""
Performs a JSON patch `add` operation.
:param path_stack: Path that describes a location in the tree, as a list, treated like a stack.
:param value: Value to add.
:returns: True if the operation was successful. False otherwise.
"""
# NOTE from the RFC:
# Because this operation is designed to add to existing objects and arrays, its target location will often
# not exist...However, the object itself or an array containing it does need to exist
# In other words, the patch op will, at most, create 1 new path level. In addition, that also implies that
# trying to append to an existing list only applies if the append operator is at the end of the list.
node, virt_idx, phys_idx, path_to_create, append_to_list = self._patch_add_find_target(path_stack)
if not RecipeParser._is_valid_patch_node(node, virt_idx):
return False
# If we couldn't find 1 level in the path, ensure that we re-insert that as the "root" of the sub-tree we are
# about to create.
if path_to_create:
value = {path_to_create: value}
new_children: list[Node] = RecipeReader._generate_subtree(value)
# Mark children as list members if they are list members
if append_to_list or phys_idx > INVALID_IDX:
# Adding an object to a list requires the children to be wrapped in a collection node
if not isinstance(value, PRIMITIVES_TUPLE):
new_children = [Node(list_member_flag=True, children=new_children)]
else:
for child in new_children:
child.list_member_flag = True
# Insert members if an index is specified. Otherwise, extend the list of child nodes from the existing list.
if phys_idx > INVALID_IDX:
node.children[phys_idx:phys_idx] = new_children
# Extend the list of children if we're appending or adding a new key.
elif append_to_list or path_to_create:
node.children.extend(new_children)
# NOTE from the RFC: "If the member already exists, it is replaced by the specified value."
else:
node.children = new_children
return True
def _patch_remove(self, path_stack: StrStack) -> bool:
"""
Performs a JSON patch `remove` operation.
:param path_stack: Path that describes a location in the tree, as a list, treated like a stack.
:returns: True if the operation was successful. False otherwise.
"""
if len(path_stack) == 0:
return False
# Removal in all scenarios requires targeting the parent node.
node_idx = -1 if not path_stack[0].isdigit() else int(path_stack[0])
# `traverse()` is destructive to the stack, so make a copy for the second traversal call.
path_stack_copy = path_stack.copy()
node_to_rm = traverse(self._root, path_stack)
if not RecipeParser._is_valid_patch_node(node_to_rm, -1):
return False
path_stack_copy.pop(0)
node = traverse(self._root, path_stack_copy)
if not RecipeParser._is_valid_patch_node(node, node_idx):
return False
if node_idx > INVALID_IDX:
# Pop the "physical" index, not the "virtual" one to ensure comments have been accounted for.
node.children.pop(remap_child_indices_virt_to_phys(node.children)[node_idx])
return True
# In all other cases, the node to be removed must be found before eviction
for i in range(len(node.children)):
if node.children[i] == node_to_rm:
node.children.pop(i)
return True
return False
def _patch_replace(self, path_stack: StrStack, value: JsonType) -> bool:
"""
Performs a JSON patch `replace` operation.
:param path_stack: Path that describes a location in the tree, as a list, treated like a stack.
:param value: Value to update with.
:returns: True if the operation was successful. False otherwise.
"""
node, virt_idx, phys_idx = traverse_with_index(self._root, path_stack)
if not RecipeParser._is_valid_patch_node(node, virt_idx):
return False
new_children: list[Node] = RecipeReader._generate_subtree(value)
# Lists inject all children at the target position.
if phys_idx > INVALID_IDX:
# Adding an object to a list requires the children to be wrapped in a collection node
if not isinstance(value, PRIMITIVES_TUPLE):
new_children = [Node(list_member_flag=True, children=new_children)]
else:
# Ensure all children are marked as list members
for child in new_children:
child.list_member_flag = True
node.children[phys_idx:phys_idx] = new_children
# Evict the old child, which is now behind the new children
node.children.pop(phys_idx + len(new_children))
return True
# Leafs that represent values/paths of values can evict all children, and be replaced with new children, derived
# from a new tree of values.
node.children = new_children
return True
def _patch_move(self, path_stack: StrStack, value_from: str) -> bool:
"""
Performs a JSON patch `add` operation.
:param path_stack: Path that describes a location in the tree, as a list, treated like a stack.
:param value_from: The "from" value in the JSON payload, i.e. the path the value originates from.
:returns: True if the operation was successful. False otherwise.
"""
# NOTE from the RFC:
# This operation is functionally identical to a "remove" operation on the "from" location, followed
# immediately by an "add" operation at the target location with the value that was just removed.
# So to save on development and maintenance, that is how this op is written.
original_value: JsonType
try:
original_value = self.get_value(value_from)
except KeyError:
return False
# Validate that `add` will succeed before we `remove` anything
node, virt_idx, _, _, _ = self._patch_add_find_target(path_stack.copy())
if not RecipeParser._is_valid_patch_node(node, virt_idx):
return False
return self._patch_remove(str_to_stack_path(value_from)) and self._patch_add(path_stack, original_value)
def _patch_copy(self, path_stack: StrStack, value_from: str) -> bool:
"""
Performs a JSON patch `add` operation.
:param path_stack: Path that describes a location in the tree, as a list, treated like a stack.
:param value_from: The "from" value in the JSON payload, i.e. the path the value originates from.
:returns: True if the operation was successful. False otherwise.
"""
# NOTE from the RFC:
# This operation is functionally identical to an "add" operation at the target location using the value
# specified in the "from" member.
# So to save on development and maintenance, that is how this op is written.
original_value: JsonType
try:
original_value = self.get_value(value_from)
except KeyError:
return False
return self._patch_add(path_stack, original_value)
def _patch_test(self, path: str, value: JsonType) -> bool:
"""
Performs a JSON patch `test` operation.
:param path: Path as a string. Useful for invoking public class members.
:param value: Value to evaluate against.
:returns: True if the target value is equal to the provided value. False otherwise.
"""
try:
return self.get_value(path) == value
except KeyError:
# Path not found
return False
def _call_patch_op(self, op: str, path: str, patch: JsonPatchType) -> bool:
"""
Switching function that calls the appropriate JSON patch operation.
:param op: Patch operation, pre-sanitized.
:param path: Path as a string.
:param patch: The original JSON patch. This is passed to conditionally provide extra arguments, per op.
:returns: True if the patch was successful. False otherwise.
"""
path_stack: Final[StrStack] = str_to_stack_path(path)
# NOTE: The `remove` op has no `value` or `from` field to pass in, so it is executed first.
if op == "remove":
return self._patch_remove(path_stack)
# The supplemental field name is determined by the operation type.
value_from: Final[str] = "from" if op in RecipeParser._patch_ops_requiring_from else "value"
patch_data: Final[JsonType | str] = patch[value_from]
if op == "add":
return self._patch_add(path_stack, patch_data)
if op == "replace":
return self._patch_replace(path_stack, patch_data)
if op == "move":
return self._patch_move(path_stack, cast(str, patch_data))
if op == "copy":
return self._patch_copy(path_stack, cast(str, patch_data))
if op == "test":
return self._patch_test(path, patch_data)
# This should be unreachable but is kept for completeness.
return False
[docs]
def patch(self, patch: JsonPatchType) -> bool:
"""
Given a JSON-patch object, perform a patch operation.
Modifications from RFC 6902
- We're using a Jinja-formatted YAML file, not JSON
- To modify comments, specify the `path` AND `comment`
:param patch: JSON-patch payload to operate with.
:raises JsonPatchValidationException: If the JSON-patch payload does not conform to our schema/spec.
:returns: If the calling code attempts to perform the `test` operation, this indicates the return value of the
`test` request. In other words, if `value` matches the target variable, return True. False otherwise. For
all other operations, this indicates if the operation was successful.
"""
# Validate the patch schema
try:
schema_validate(patch, JSON_PATCH_SCHEMA)
except Exception as e:
raise JsonPatchValidationException(patch) from e
path: Final[str] = cast(str, patch["path"])
# All RFC ops are supported, so the JSON schema validation checks will prevent us from getting this far, if
# there is an issue.
op: Final[str] = cast(str, patch["op"])
# A no-op move is silly, but we might as well make it efficient AND ensure a no-op move doesn't corrupt our
# modification flag.
if op == "move" and path == patch["from"]:
return True
# Both versions of the path are sent over so that the op can easily use both private and public functions
# (without incurring even more conversions between path types).
is_successful = self._call_patch_op(op, path, patch)
# Update the selector table and modified flag, if the operation succeeded.
if is_successful and op != "test":
# TODO this is not the most efficient way to update the selector table, but for now, it works.
self._rebuild_selectors()
# TODO technically this doesn't handle a no-op.
self._is_modified = True
return is_successful
[docs]
def search_and_patch(
self, regex: str | re.Pattern[str], patch: JsonPatchType, include_comment: bool = False
) -> bool:
"""
Given a regex string and a JSON patch, apply the patch to any values that match the search expression.
:param regex: Regular expression to match with
:param patch: JSON patch to perform. NOTE: The `path` field will be replaced with the path(s) found, so it does
not need to be provided.
:param include_comment: (Optional) If set to `True`, this function will execute the regular expression on values
WITH their comments provided. For example: `42 # This is a comment`
:returns: Returns a list of paths where the matched value was found.
"""
paths = self.search(regex, include_comment)
summation: bool = True
for path in paths:
patch["path"] = path
summation = summation and self.patch(patch)
return summation
[docs]
def diff(self) -> str:
"""
Returns a git-like-styled diff of the current recipe state with original state of the recipe. Useful for
debugging and providing users with some feedback.
:returns: User-friendly displayable string that represents notifications made to the recipe.
"""
if not self.is_modified():
return ""
# Utilize `difflib` to lower maintenance overhead.
return "\n".join(
difflib.unified_diff(
self._init_content.splitlines(), self.render().splitlines(), fromfile="original", tofile="current"
)
)