The main new finction is is(), which tests the type of a value. There
are also constants for each of the possible token types, and one new
conversion: number(), which converts a value into the most appropriate number
type. This change also reuses the functions in scanner.h for exracting ints,
floats, and identifiers from strings, rather than either rewriting the
functionality elsewhere, or using the general-purpose scan when only one
token type was of interest.
The primary change is to add a “funcall” token, so that an entire expression
can be encapsulated as a single token. This change is used to allow a cell to
include simply a selection of appropriate semantic tokens. I.e., the content
and iterative content are now each a single token like the value and the
result value. Token vectors are used only as intermediate results in scanning
and parsing.
Not this means the cells are now in effect storing parse trees, so
computation should be slightly faster and future extensions (like #56) should
be facilitated.
This commit also takes the opportunity while internals are being altered to
add another token to a cell for future use for computed attributes, cf #22,
and to change the internal numerical values from double and ints to long
doubles and long longs. However, the change attempts to encapsulate that
choice so it would be easy to change back or change to another representation.
Note that these changes break savexdr(), as the internal binary format of
a cell is now different. Rather than reimplement it, it is deprecated as
the world does not need another binary spreadsheet format. Hence, the
ascii format for teapot spreadsheets becomes the primary file format.
Loading of old xdr files is still supported for backward compatibility.
Closes#59.
Also along the way, various other slight fixes and enhancements crept in,
a partial but probably not exhaustive list of which follows:
Fixes#31.
Further revisions and improvements to documentation.
Make the approximate comparison of floating point values scale more
accurately with the size of the doubles being compared.
Further extensions of absolute and relative cell addressing.
Addition of (circle constant) tau function/constant.
Modified string conversion to simply use internal printing routines, and
to take "scientific" and "decimal" keywords.
Allowed n() function to take a list of values, or just a single location
defaulting to the current location.
Added floor, ceil, trunc, and round functions, and allowed them to be
keywords controlling the int() integer conversion function as well.
Allowed substr() to drop its last argument to go to the end of the string.
Provided an enum of built-in functions to preserve legacy function
identifiers, allowing the large table inside func.c to be reorganized
in a clearer fashion.
Added additional annotation of properties of the built-in functions,
including precedence.
All operators are now also accessible as built-in functions.
Made precedence of unary - lower than ^ to match python.
Avoided inadvertently using FLTK @symbol abbreviations for formulas with
"@" in them.
The new function is X(SRC,REF), which briefly for a cell in the neighborhood
of REF returns the corresponding cell in the neighborhood in SRC. For
further details, see the updated documention.
In developing and documenting this function, I refined some of the
existing error messages (e.g. showing the coordinates when there is an
attempt to obtain a cell with a negative coordinate) and improved the
error propagation to increase the chance that the innermost error will
percolate to the top level.
Glen Whitney