reprexlite.code

Attributes

NO_RETURN

Explicit placeholder object for statements, which have no return value (as opposed to expressions).

Classes

CodeBlock

Class that takes a block of Python code input and evaluates it. Call str(...) on an instance to get back a string containing the original source with evaluated outputs embedded as comments below each statement.

Attributes:

Name	Type	Description
input	str	Block of Python code
style	bool	Whether to use black to autoformat code in returned string representation.
comment	str	Line prefix to use when rendering the evaluated results.
terminal	bool	Whether to apply syntax highlighting to the string representation. Requires optional dependency Pygments.
tree	libcst.Module	Parsed LibCST concrete syntax tree of input code.
statements	List[Statement]	List of individual statements parsed from input code.
results	List[Result]	List of evaluated results corresponding to each item of statements.

Source code in reprexlite/code.py

class CodeBlock:
    """Class that takes a block of Python code input and evaluates it. Call `str(...)` on an
    instance to get back a string containing the original source with evaluated outputs embedded
    as comments below each statement.

    Attributes:
        input (str): Block of Python code
        style (bool): Whether to use black to autoformat code in returned string representation.
        comment (str): Line prefix to use when rendering the evaluated results.
        terminal (bool): Whether to apply syntax highlighting to the string representation.
            Requires optional dependency Pygments.
        tree (libcst.Module): Parsed LibCST concrete syntax tree of input code.
        statements (List[Statement]): List of individual statements parsed from input code.
        results (List[Result]): List of evaluated results corresponding to each item of statements.
    """

    def __init__(
        self,
        input: str,
        style: bool = False,
        comment: str = "#>",
        terminal=False,
        old_results: bool = False,
    ):
        """Initializer method.

        Args:
            input (str): Block of Python code
            style (bool): Whether to use black to autoformat code in returned string
                representation. Defaults to False.
            comment (str): Line prefix to use when rendering the evaluated results. Defaults to
                "#>".
            terminal (bool): Whether to apply syntax highlighting to the string representation.
                Requires optional dependency Pygments. Defaults to False.
            old_results (bool): Whether to keep old results, i.e., comment lines in input that
                match the `comment` prefix. False means these lines are removed, in effect meaning
                an inputted regex will have its results regenerated. Defaults to False.
        """
        if any(line.startswith(">>>") for line in input.split("\n")):
            input = repl_to_reprex_code(input, comment=comment)
        if not old_results and comment in input:
            input = "\n".join(line for line in input.split("\n") if not line.startswith(comment))
        self.input: str = input
        self.terminal = terminal
        # Parse code
        self.tree: cst.Module = cst.parse_module(input)
        self.statements: List[Statement] = [
            Statement(stmt, style=style) for stmt in self.tree.body
        ]
        # Evaluate code
        self.namespace: dict = {}
        self.results: List[Result] = [stmt.evaluate(self.namespace) for stmt in self.statements]
        for res in self.results:
            res.comment = comment

    def __str__(self):
        header = cst.Module(body=[], header=self.tree.header).code.strip()
        code = "\n".join(
            str(line) for line in chain.from_iterable(zip(self.statements, self.results)) if line
        )
        footer = cst.Module(body=[], footer=self.tree.footer).code.strip()
        out = "\n".join([header, code, footer])
        if self.terminal:
            try:
                from pygments import highlight
                from pygments.formatters import Terminal256Formatter
                from pygments.lexers import PythonLexer

                out = highlight(out, PythonLexer(), Terminal256Formatter(style="friendly"))
            except ImportError:
                pass
        return out.strip()

    def _repr_html_(self):
        out = []
        try:
            from pygments import highlight
            from pygments.formatters import HtmlFormatter
            from pygments.lexers import PythonLexer

            formatter = HtmlFormatter(style="friendly", wrapcode=True)
            out.append(f"<style>{formatter.get_style_defs('.highlight')}</style>")
            out.append(highlight(str(self), PythonLexer(), formatter))
        except ImportError:
            out.append(f"<pre><code>{self}</code></pre>")
        return "\n".join(out)

Methods

__init__(self, input, style=False, comment='#>', terminal=False, old_results=False) special

Initializer method.

Parameters:

Name	Type	Description	Default
input	str	Block of Python code	required
style	bool	Whether to use black to autoformat code in returned string representation. Defaults to False.	False
comment	str	Line prefix to use when rendering the evaluated results. Defaults to "#>".	'#>'
terminal	bool	Whether to apply syntax highlighting to the string representation. Requires optional dependency Pygments. Defaults to False.	False
old_results	bool	Whether to keep old results, i.e., comment lines in input that match the comment prefix. False means these lines are removed, in effect meaning an inputted regex will have its results regenerated. Defaults to False.	False

Source code in reprexlite/code.py

def __init__(
    self,
    input: str,
    style: bool = False,
    comment: str = "#>",
    terminal=False,
    old_results: bool = False,
):
    """Initializer method.

    Args:
        input (str): Block of Python code
        style (bool): Whether to use black to autoformat code in returned string
            representation. Defaults to False.
        comment (str): Line prefix to use when rendering the evaluated results. Defaults to
            "#>".
        terminal (bool): Whether to apply syntax highlighting to the string representation.
            Requires optional dependency Pygments. Defaults to False.
        old_results (bool): Whether to keep old results, i.e., comment lines in input that
            match the `comment` prefix. False means these lines are removed, in effect meaning
            an inputted regex will have its results regenerated. Defaults to False.
    """
    if any(line.startswith(">>>") for line in input.split("\n")):
        input = repl_to_reprex_code(input, comment=comment)
    if not old_results and comment in input:
        input = "\n".join(line for line in input.split("\n") if not line.startswith(comment))
    self.input: str = input
    self.terminal = terminal
    # Parse code
    self.tree: cst.Module = cst.parse_module(input)
    self.statements: List[Statement] = [
        Statement(stmt, style=style) for stmt in self.tree.body
    ]
    # Evaluate code
    self.namespace: dict = {}
    self.results: List[Result] = [stmt.evaluate(self.namespace) for stmt in self.statements]
    for res in self.results:
        res.comment = comment

Result

Class that holds the result of evaluated code. Use str(...) on an instance to produce a pretty-formatted comment block representation of the result.

Attributes:

Name	Type	Description
result	Any	Some Python object, intended to be the return value of evaluated Python code.
comment	str	Line prefix to use when rendering the result for a reprex.

Source code in reprexlite/code.py

class Result:
    """Class that holds the result of evaluated code. Use `str(...)` on an instance to produce a
    pretty-formatted comment block representation of the result.

    Attributes:
        result (Any): Some Python object, intended to be the return value of evaluated Python code.
        comment (str): Line prefix to use when rendering the result for a reprex.
    """

    def __init__(self, result: Any, stdout: Optional[str] = None, comment: str = "#>"):
        self.result = result
        self.stdout = stdout
        self.comment = comment

    def __str__(self) -> str:
        lines = []
        if self.stdout:
            lines.extend(self.stdout.split("\n"))
        if self.result is not NO_RETURN and (self.result is not None or not self.stdout):
            # NO_RETURN -> don't print
            # None and stdout -> don't print
            # None and no stdout -> print
            # Anything else -> print
            lines.extend(pformat(self.result, indent=2, width=77).split("\n"))
        return "\n".join(f"{self.comment} " + line for line in lines)

    def __bool__(self) -> bool:
        # If result is NO_RETURN and blank stdout, nothing to print
        return self.result is not NO_RETURN or bool(self.stdout)

__init__(self, result, stdout=None, comment='#>') special

Source code in reprexlite/code.py

def __init__(self, result: Any, stdout: Optional[str] = None, comment: str = "#>"):
    self.result = result
    self.stdout = stdout
    self.comment = comment

Statement

Class that holds a LibCST parsed statement. The evaluate method will evaluate the statement and return a Result object. To recover the original source code for an instancement, call str(...) on it. You can optionally autoformat the returned source code, controlled by the style attribute.

Attributes:

Name	Type	Description
stmt	Union[libcst.SimpleStatementLine, libcst.BaseCompoundStatement]	LibCST parsed statement.
style	bool	Whether to autoformat the source code with black.

Source code in reprexlite/code.py

class Statement:
    """Class that holds a LibCST parsed statement. The evaluate method will evaluate the statement
    and return a [`Result`][reprexlite.code.Result] object. To recover the original source code
    for an instancement, call `str(...)` on it. You can optionally autoformat the returned source
    code, controlled by the `style` attribute.

    Attributes:
        stmt (Union[libcst.SimpleStatementLine, libcst.BaseCompoundStatement]): LibCST parsed
            statement.
        style (bool): Whether to autoformat the source code with black.
    """

    def __init__(
        self, stmt: Union[cst.SimpleStatementLine, cst.BaseCompoundStatement], style: bool = False
    ):
        self.stmt = stmt
        self.style = style

    def evaluate(self, scope: dict) -> Result:
        if "__name__" not in scope:
            scope["__name__"] = "__reprex__"
        stdout_io = StringIO()
        try:
            with redirect_stdout(stdout_io):
                try:
                    result = eval(str(self).strip(), scope)
                except SyntaxError:
                    exec(str(self).strip(), scope)
                    result = NO_RETURN
            stdout = stdout_io.getvalue().strip()
        except Exception as exc:
            result = NO_RETURN
            # Skip first step of traceback, since that is this evaluate method
            if exc.__traceback__ is not None:
                tb = exc.__traceback__.tb_next
                stdout = (
                    "Traceback (most recent call last):\n"
                    + "".join(line for line in traceback.format_tb(tb))
                    + f"{type(exc).__name__}: {exc}"
                )
        finally:
            stdout_io.close()
        return Result(result, stdout=stdout)

    def __str__(self) -> str:
        code = cst.Module(body=[self.stmt]).code
        if self.style:
            try:
                from black import Mode, format_str
            except ImportError:
                raise ImportError("Must install black to restyle code.")

            code = format_str(code, mode=Mode())
        if code.endswith("\n"):
            # Strip trailing newline without stripping deliberate ones.
            code = code[:-1]
        return code

__init__(self, stmt, style=False) special

Source code in reprexlite/code.py

def __init__(
    self, stmt: Union[cst.SimpleStatementLine, cst.BaseCompoundStatement], style: bool = False
):
    self.stmt = stmt
    self.style = style

evaluate(self, scope)

Source code in reprexlite/code.py

def evaluate(self, scope: dict) -> Result:
    if "__name__" not in scope:
        scope["__name__"] = "__reprex__"
    stdout_io = StringIO()
    try:
        with redirect_stdout(stdout_io):
            try:
                result = eval(str(self).strip(), scope)
            except SyntaxError:
                exec(str(self).strip(), scope)
                result = NO_RETURN
        stdout = stdout_io.getvalue().strip()
    except Exception as exc:
        result = NO_RETURN
        # Skip first step of traceback, since that is this evaluate method
        if exc.__traceback__ is not None:
            tb = exc.__traceback__.tb_next
            stdout = (
                "Traceback (most recent call last):\n"
                + "".join(line for line in traceback.format_tb(tb))
                + f"{type(exc).__name__}: {exc}"
            )
    finally:
        stdout_io.close()
    return Result(result, stdout=stdout)

Functions

repl_to_reprex_code(input, comment='#>')

Reformat a code block copied from a Python REPL to a reprex-style code block.

Parameters:

Name	Type	Description	Default
input	str	code block	required
comment	str	Line prefix to use when rendering the evaluated results. Defaults to "#>".	'#>'

Returns:

Type	Description
str	Reformatted code block in reprex-style.

Source code in reprexlite/code.py

def repl_to_reprex_code(input: str, comment: str = "#>") -> str:
    """Reformat a code block copied from a Python REPL to a reprex-style code block.

    Args:
        input (str): code block
        comment (str): Line prefix to use when rendering the evaluated results. Defaults to "#>".

    Returns:
        Reformatted code block in reprex-style.
    """
    out = []
    for line in input.split("\n"):
        if line.startswith(">>>") or line.startswith("..."):
            out.append(line[4:])
        elif line.strip() == "":
            out.append(line)
        else:
            out.append(comment + " " + line)
    return "\n".join(out)