128 lines
4.1 KiB
Python
128 lines
4.1 KiB
Python
# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2025)
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import annotations
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import ast
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import contextlib
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import re
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import textwrap
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import traceback
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from typing import TYPE_CHECKING, Any, Literal
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from streamlit.runtime.metrics_util import gather_metrics
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if TYPE_CHECKING:
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from collections.abc import Generator, Iterable
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_SPACES_RE = re.compile("\\s*")
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_EMPTY_LINE_RE = re.compile("\\s*\n")
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@gather_metrics("echo")
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@contextlib.contextmanager
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def echo(
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code_location: Literal["above", "below"] = "above",
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) -> Generator[None, None, None]:
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"""Use in a `with` block to draw some code on the app, then execute it.
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Parameters
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----------
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code_location : "above" or "below"
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Whether to show the echoed code before or after the results of the
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executed code block.
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Example
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-------
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>>> import streamlit as st
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>>>
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>>> with st.echo():
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>>> st.write('This code will be printed')
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"""
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from streamlit import code, empty, source_util, warning
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if code_location == "below":
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show_code = code
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show_warning = warning
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else:
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placeholder = empty()
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show_code = placeholder.code
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show_warning = placeholder.warning
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try:
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# Get stack frame *before* running the echoed code. The frame's
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# line number will point to the `st.echo` statement we're running.
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frame = traceback.extract_stack()[-3]
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filename, start_line = frame.filename, frame.lineno or 0
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# Read the file containing the source code of the echoed statement.
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with source_util.open_python_file(filename) as source_file:
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source_lines = source_file.readlines()
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# Use ast to parse the Python file and find the code block to display
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root_node = ast.parse("".join(source_lines))
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line_to_node_map: dict[int, Any] = {}
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def collect_body_statements(node: ast.AST) -> None:
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if not hasattr(node, "body"):
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return
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for child in ast.iter_child_nodes(node):
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# If child doesn't have "lineno", it is not something we could display
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if hasattr(child, "lineno"):
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line_to_node_map[child.lineno] = child
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collect_body_statements(child)
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collect_body_statements(root_node)
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# In AST module the lineno (line numbers) are 1-indexed,
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# so we decrease it by 1 to lookup in source lines list
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echo_block_start_line = line_to_node_map[start_line].body[0].lineno - 1
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echo_block_end_line = line_to_node_map[start_line].end_lineno
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lines_to_display = source_lines[echo_block_start_line:echo_block_end_line]
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code_string = textwrap.dedent("".join(lines_to_display))
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# Run the echoed code...
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yield
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# And draw the code string to the app!
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show_code(code_string, "python")
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except FileNotFoundError as err:
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show_warning(f"Unable to display code. {err}")
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def _get_initial_indent(lines: Iterable[str]) -> int:
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"""Return the indent of the first non-empty line in the list.
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If all lines are empty, return 0.
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"""
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for line in lines:
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indent = _get_indent(line)
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if indent is not None:
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return indent
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return 0
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def _get_indent(line: str) -> int | None:
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"""Get the number of whitespaces at the beginning of the given line.
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If the line is empty, or if it contains just whitespace and a newline,
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return None.
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"""
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if _EMPTY_LINE_RE.match(line) is not None:
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return None
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match = _SPACES_RE.match(line)
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return match.end() if match is not None else 0
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