SyntaxErrorLocation.h File Reference

Finds where in a code cell a Maxima syntax error is (GH #289). More...

#include <wx/string.h>
#include <optional>

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Data Structures
struct	wxm::TextRange
	A range of characters in a cell's text: [start, end) More...

Functions
std::optional< wxString >	wxm::SyntaxErrorEcho (const wxString &maximaOutput)
	The line Maxima echoes under its first "incorrect syntax:" message.
std::optional< TextRange >	wxm::LocateSyntaxError (const wxString &maximaOutput, const wxString &cellText, TextRange statement)
	Where in a cell the syntax error Maxima reported is.

Detailed Description

Finds where in a code cell a Maxima syntax error is (GH #289).

wxMaxima sends a cell to Maxima one statement at a time, so it always knows which statement an error belongs to. For a syntax error Maxima also tells where in that statement it gave up – but only as text, for a human: its parser (mread-synerr in Maxima's nparse.lisp) prints

incorrect syntax: , is not a prefix operator
f(a,,
   ^

i.e. the message, then the last (up to 20) characters of the current line it has read, then a caret. The second line ends where the parser stopped reading, which is at, or one character after, the offending token.

This file reads that text and finds the same characters in the statement. It deliberately changes nothing in Maxima and hooks none of its functions: it only reads what Maxima prints anyway, the same way wxMaxima already recognises an error at all by the words "incorrect syntax". If a future Maxima prints something else, LocateSyntaxError() finds nothing, and the worksheet falls back to marking the whole statement.

Two quirks of real Maxima versions are handled:

• Maxima 5.46 prints a space in that line as the word "Space" (and a tab as "Tab"); newer versions print the characters themselves.
• The line stops at a newline, so for a statement spanning several lines it is the tail of the line the error is in.

GUI-free, so test_SyntaxErrorLocation can pin it directly.

Function Documentation

LocateSyntaxError()

std::optional< TextRange > wxm::LocateSyntaxError	(	const wxString &	maximaOutput,
		const wxString &	cellText,
		TextRange	statement
	)

Where in a cell the syntax error Maxima reported is.

Parameters

maximaOutput	Everything Maxima printed in reply to one statement.
cellText	The text of the code cell the statement came from.
statement	The statement's characters in cellText.

Returns

The characters to mark: the token Maxima stopped at, plus the one character after it it may have read ahead. Nothing if Maxima did not report a syntax error, or the echoed text can't be found in the statement (for example because wxMaxima stripped a comment from it before sending it).

SyntaxErrorEcho()

std::optional< wxString > wxm::SyntaxErrorEcho

(

const wxString &

maximaOutput

)

The line Maxima echoes under its first "incorrect syntax:" message.

Parameters

maximaOutput

Everything Maxima printed in reply to one statement.

Returns

The echoed input line, exactly as Maxima printed it, or nothing if the output contains no complete syntax error report (the caret line is what tells that the echo is complete).