syntax

tuprolog.solve.exception.error.syntax ¶

Syntax errors: some text being read is not valid Prolog.

ISO Prolog's syntax_error error, thrown as error(syntax_error, Extra), means that a sequence of characters being read does not conform to Prolog's grammar: e.g. reading f( by read/1, or converting it to a term by term_to_atom/2. Errors of Python code parsing text (see tuprolog.core.parsing) are tuprolog.errors.ParsingErrors instead, not logic errors.

The error is a SyntaxError (the JVM class: import it explicitly, as it shadows Python's built-in name). Build errors with syntax_error, syntax_error_while_parsing_term, or syntax_error_while_parsing_clauses; error_detector points at the offending character of a text.

Examples:

>>> from tuprolog.solve import signature
>>> from tuprolog.solve.exception.error import *
>>> from tuprolog.solve.prolog import prolog_solver
>>> context = prolog_solver().current_context
>>> syntax_error_while_parsing_term(context, "f(", 1, 3, "unexpected end").error_struct
error(syntax_error, 'Syntax error at 1:3 while parsing `f(`: unexpected end')

syntax_error ¶

syntax_error(
    context: ExecutionContext, message: str
) -> SyntaxError

Creates a syntax error with a message, without positional information.

Parameters:

Name	Type	Description	Default
`context`	`ExecutionContext`	the execution context in which the error occurs (e.g. a request's `context`).	required
`message`	`str`	the error message.	required

Returns:

Type	Description
`SyntaxError`	The error, thrown as `error(syntax_error, Message)`.

Examples:

>>> from tuprolog.solve import signature
>>> from tuprolog.solve.exception.error import *
>>> from tuprolog.solve.prolog import prolog_solver
>>> context = prolog_solver().current_context
>>> syntax_error(context, "missing dot").message
'Syntax error: missing dot'

syntax_error_while_parsing_term ¶

syntax_error_while_parsing_term(
    context: ExecutionContext,
    input: str,
    row: int,
    column: int,
    message: str,
) -> SyntaxError

Creates the syntax error for some text failing to parse as a term.

Parameters:

Name	Type	Description	Default
`context`	`ExecutionContext`	the execution context in which the error occurs (e.g. a request's `context`).	required
`input`	`str`	the text being parsed.	required
`row`	`int`	the (1-based) line where parsing failed.	required
`column`	`int`	the (1-based) column where parsing failed.	required
`message`	`str`	the detail message.	required

Returns:

Type	Description
`SyntaxError`	The error, thrown as `error(syntax_error, Message)`.

Examples:

>>> from tuprolog.solve import signature
>>> from tuprolog.solve.exception.error import *
>>> from tuprolog.solve.prolog import prolog_solver
>>> context = prolog_solver().current_context
>>> syntax_error_while_parsing_term(context, "f(", 1, 3, "unexpected end").message
'Syntax error at 1:3 while parsing `f(`: unexpected end'

syntax_error_while_parsing_clauses ¶

syntax_error_while_parsing_clauses(
    context: ExecutionContext,
    input: str,
    index: int,
    row: int,
    column: int,
    message: str,
) -> SyntaxError

Creates the syntax error for a clause of some text failing to parse.

The message shows the offending lines, with a caret (^) under the offending column (see error_detector).

Parameters:

Name	Type	Description	Default
`context`	`ExecutionContext`	the execution context in which the error occurs (e.g. a request's `context`).	required
`input`	`str`	the text being parsed, e.g. a theory.	required
`index`	`int`	the index of the clause failing to parse.	required
`row`	`int`	the (1-based) line where parsing failed.	required
`column`	`int`	the (1-based) column where parsing failed.	required
`message`	`str`	the detail message.	required

Returns:

Type	Description
`SyntaxError`	The error, thrown as `error(syntax_error, Message)`.

error_detector ¶

error_detector(
    text: str,
    line: int,
    column: int,
    message: str | None = None,
) -> str

Renders a line of a text with a caret (^) under a column, for error messages.

The previous line, if any, is shown as well, for context.

Parameters:

Name	Type	Description	Default
`text`	`str`	the text.	required
`line`	`int`	the (1-based) line to show.	required
`column`	`int`	the (1-based) column to point at.	required
`message`	`str \| None`	a message to append after the caret, if any.	`None`

Returns:

Type	Description
`str`	The rendered lines, each prefixed by its number.

Examples:

>>> from tuprolog.solve.exception.error.syntax import error_detector
>>> print(error_detector("foo(bar baz)", 1, 9, "unexpected"))
1: foo(bar baz)
           ^ unexpected