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fix: Always compute cells without clocked expressions using current values #91

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glen merged 2 commits from contemporaneous_references into main 2023-04-30 16:19:13 +00:00
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5 changed files with 222 additions and 39 deletions
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16
NEWS
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@ -6,6 +6,13 @@ The changes compared to 2.3.0 are:
o Added examples updating the life simulation to illustrate the color and
computed style features.
o You can compute the styles for cells, with an additional expression per cell.
o Computation of current values for cells without clocked expressions now
always depends on contemporaneous current values rather than prior values,
even when the sheet is clocked. This means, for example, an entry whose base
value is the sum of a column and which has no will always resolve to the
current sum of that column, even if the column contains clocked values.
(This is a breaking change in that prior to this modification, such a cell
when clocked would contain the sum of the prior values in that column.)
o New token types: style and bool.
o Comparison operators return bool rather than int (Note this can be a breaking
change; you may need to wrap comparisons in int() if you are using the result
@ -21,8 +28,13 @@ o Addition of hexact float format, which allows for exact round trips to ASCII
o New token type: funcall (which basically amounts to an expression). This
allows parsed rather than unparsed expressions to be stored in cells, and
allows macros which receive their arguments unevaluated.
o sum(), min(), and max() can now operate over their list of arguments as well
as over a block.
o New region/accumulator operation count() that counts truthy cells (rather
that just nonempty cells as n() does) added.
o All region/accumulator operations including sum(), min(), and max() can
now operate over their list of arguments as well as over a block.
o All region/accumulator operations can take an optional expression when
operating over a block that generates the values to be accumulated (rather
than just taking the values directly from the block).
o Added floor(), ceil(), trunc(), and round() functions for finding integers
associated with doubles, eliminating (note possible breaking change) the
int conversion with two rounding directions.

170
doc/teapot.lyx
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@ -346,7 +346,7 @@ name "fig:Three-Dimensional-Spread-Sheet"
\end_inset
Three-Dimensional Spread Sheet Layout
Three-Dimensional Spreadsheet Layout
\end_layout
\end_inset
@ -794,7 +794,7 @@ The sheet is currently in reset condition and the result is 1.
\begin_layout Standard
After this introductory chapter, you should be familiar with the basic concepts
in spread sheets.
in spreadsheets.
The next chapters explain all operations available in detail.
You should read them to get an overview of the possibilities offered by
@ -4595,7 +4595,7 @@ CSV (.csv)
\begin_layout Standard
CSV (comma separated value) files only contain the data, not the expressions
calculating it.
Many spread sheets can generate this file format and many graphics programs
Many spreadsheets can generate this file format and many graphics programs
like gnuplot(1) can read it.
The field separator usually is a tab or comma, strings may be enclosed
in double quotes and decimal numbers have a dot to mark the fractional
@ -5315,34 +5315,170 @@ goto
5.12.4
\emph default
.
\end_layout
\begin_layout Section
Expressions
Sheets, Cells, and Clocking
\end_layout
\begin_layout Standard
Cells consist of a base (reset) expression, a clocked expression, a style
expression, and a current value.
If the sheet is currently in the reset state (the default), all cells display
their base value as current value.
A
\emph on
sheet
\emph default
is a three-dimensional collection of
\emph on
cells
\emph default
.
The slices in the X, Y, and Z directions are called the
\emph on
columns
\emph default
,
\emph on
rows
\emph default
, and
\emph on
layers
\emph default
, respectively.
At any given time, the valid coordinates for a sheet are all non-negative
integers up to some current limit in each of the X, Y, and Z directions,
which may be different in each direction.
Generally speaking, direct references to cells with negative coordinates
are an error, whereas indirect references to cells with negative coordinates
and all references to cells with coordinates beyond the current limits
act as references to empty cells with all default attributes/styles.
\end_layout
\begin_layout Standard
When the sheet is clocked (see Table
Each cell has three expressions, all of which are optional: a base (reset)
expression, a clocked expression, and a style expression.
It also has an associated current value.
See section
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Expressions"
plural "false"
caps "false"
noprefix "false"
\end_inset
for the semantics of expressions and values.
When the sheet is in the reset state (the default/initial state), all cells
set their current values to the value of their base expression; references
to other cells use those other cells' current values.
The recomputation of current values updates referred-to cells first in
an effort to produce the expected, correct values.
However, if there are circular references among cells, this update process
does not attempt to produce a fully self-consistent state, in that a given
cell is only updated once.
Hence the resulting current values can depend on the order updates occur,
and it may happen that a cell's current value is not equal to the value
of its base expression computed with current values of all cells.
This behavior may seem problematic, but in fact it's not always possible
to produce a self-consistent state.
The simplest example is if the base expression for the cell with coordinates
(0,0,0) is @(0,0,0)+1, since no number is one more than itself.
Moreover, in the absence of circular reference chains among the base expression
s, the recomputation of current values is guaranteed to reach a consistent
state for all cells.
The bottom line is that although circular references in base expressions
are not disallowed, their utility may be limited because their behavior
is relatively unpredictable.
\end_layout
\begin_layout Standard
When a sheet is clocked (see Table
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Key-Bindings-in"
\end_inset
), the clocked expression is evaluated, using the current value of referenced
cells.
The new current value is the result of that evaluation.
), every cell with a clocked expression is clocked.
When a cell is clocked (either because the sheet was clocked or by virtue
of the clock() function documented in section
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:All-other-functions"
plural "false"
caps "false"
noprefix "false"
\end_inset
), its clocked expression is evaluated using the current value of all cells
referenced directly or indirectly, including cells that are also currently
being clocked.
Then the new current value of (all of the) clocked cell(s) is set to the
result of that evaluation.
Finally, the current values of the unclocked cells (which include any cells
that have no clocked expression) are recomputed based on the new current
values.
The upshot of these rules is that one can control the updating of potentially
circular references precisely: the computation of clocked expressions always
uses values of all cells, including other clocked cells, from the previous
\begin_inset Quotes eld
\end_inset
tick
\begin_inset Quotes erd
\end_inset
, and the computation of base expressions uses values of all cells, including
other unclocked cells, from the current tick.
\end_layout
\begin_layout Standard
Finally, whenever the style of a given cell is needed, for example to display
the cell, its style expression is evaluated based on the current values
of all cells to which it refers directly or indirectly.
The expression must evaluate to a style value (see subsection
\begin_inset CommandInset ref
LatexCommand ref
reference "subsec:Data-Types"
plural "false"
caps "false"
noprefix "false"
\end_inset
) and that value provides the style of the cell.
\end_layout
\begin_layout Section
\begin_inset CommandInset label
LatexCommand label
name "sec:Expressions"
\end_inset
Expressions and values
\end_layout
\begin_layout Standard
In
\noun on
teapot
\noun default
, values are specific data items and expressions are the formulas that can
be evaluated to produce those values.
This section describes the possible values, the allowed syntax of expressions,
and the semantics of valid expressions.
\end_layout
\begin_layout Subsection
\begin_inset CommandInset label
LatexCommand label
name "subsec:Data-Types"
\end_inset
Data Types
\end_layout
@ -6996,6 +7132,12 @@ sum Returns the sum of the accumulated values (recall for strings this is
\end_layout
\begin_layout Subsubsection
\begin_inset CommandInset label
LatexCommand label
name "subsec:All-other-functions"
\end_inset
All other functions
\end_layout
@ -10123,7 +10265,7 @@ How do I hide intermediate results?
\end_layout
\begin_layout Standard
If you used flat, two-dimensional spread sheets before, you are probably
If you used flat, two-dimensional spreadsheets before, you are probably
used to hidden cells which contain intermediate results, global constants,
scratch areas and the like.

13
src/common/cell.c
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@ -33,9 +33,9 @@ void initcellcontents(Cell *fresh)
fresh->updated = false;
fresh->locked = false;
fresh->ignored = false;
fresh->clock_t0 = false;
fresh->clock_t1 = false;
fresh->clock_t2 = false;
fresh->use_iter_cont = false;
fresh->clock_resolving = false;
fresh->clock_requested = false;
}
/* getcont -- get contents */
@ -45,11 +45,16 @@ Token gettok(const Cell *cell, TokVariety v)
emp.type = EMPTY;
if (cell == NULLCELL) return emp;
if (v == CONTINGENT)
v = (cell->clock_t0 && cell->tok[ITER_CONT].type != EMPTY)
v = (cell->use_iter_cont && cell->tok[ITER_CONT].type != EMPTY)
? ITER_CONT : BASE_CONT;
return cell->tok[v];
}
/* iterable -- does cell have iteration content? */
bool iterable(const Cell* cell) {
return (cell != NULLCELL) && cell->tok[ITER_CONT].type != EMPTY;
}
/* locked -- is cell locked? */
bool locked(const Cell *cell)
{

7
src/common/cell.h
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@ -22,9 +22,9 @@ typedef struct
unsigned int updated:1;
unsigned int locked:1;
unsigned int ignored:1;
unsigned int clock_t0:1;
unsigned int clock_t1:1;
unsigned int clock_t2:1;
unsigned int use_iter_cont:1;
unsigned int clock_resolving:1;
unsigned int clock_requested:1;
} Cell;
#define NULLCELL ((Cell*)0)
@ -32,6 +32,7 @@ typedef struct
typedef enum {ALTER_LABEL, PRESERVE_LABEL} LabelHandling;
Token gettok(const Cell *cell, TokVariety v);
bool iterable(const Cell *cell);
bool locked(const Cell *cell);
bool ignored(const Cell *cell);
const char *getlabel(const Cell *cell);

53
src/common/sheet.c
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@ -104,9 +104,9 @@ static void dump_cell(Sheet *sheet, int x, int y, int z)
if (c->updated) printf(" updated ");
if (c->locked) printf(" locked ");
if (c->ignored) printf(" ignored ");
if (c->clock_t0) printf(" clock_t0 ");
if (c->clock_t1) printf(" clock_t1 ");
if (c->clock_t2) printf(" clock_t2 ");
if (c->use_iter_cont) printf(" use_iter_cont ");
if (c->clock_resolving) printf(" clock_resolving ");
if (c->clock_requested) printf(" clock_requested ");
printf("\n\n");
}
/*}}}*/
@ -448,7 +448,7 @@ void forceupdate(Sheet *sheet)
size_t i; Cell *cell;
for (ALL_CELLS_IN_SHEET(sheet,i,cell))
if (cell != NULLCELL) {
cell->updated = cell->clock_t0 = cell->clock_t1 = cell->clock_t2 = false;
cell->updated = cell->use_iter_cont = cell->clock_resolving = cell->clock_requested = false;
tfree(&(cell->tok[STYLE_VAL]));
}
update(sheet);
@ -613,7 +613,7 @@ Token recompvalue(Sheet *sheet, const Location at)
upd_sheet = sheet;
LOCATION_GETS(upd_l, at);
max_eval = MAX_EVALNEST;
if (!(cell->clock_t1))
if (!(cell->clock_resolving))
{
cell->updated = true;
oldvalue = gettok(cell, CURR_VAL);
@ -633,6 +633,9 @@ Token recompvalue(Sheet *sheet, const Location at)
LOCATION_GETS(upd_l, old_l);
max_eval = old_max_eval;
}
/* When upd_clock was true on entry, the result is going to be thrown
away in any case, so don't bother doing the copy.
*/
if (!orig_upd_clock) result = tcopy(cell->tok[CURR_VAL]);
/*}}}*/
return result;
@ -666,7 +669,7 @@ void update(Sheet *sheet)
sheet->clk = 0;
if (iterating == 1)
{
line_msg(NULL, _("Realculation running, press Escape to abort it"));
line_msg(NULL, _("Recalculation running, press Escape to abort it"));
++iterating;
}
else if (iterating == 0) ++iterating;
@ -674,12 +677,12 @@ void update(Sheet *sheet)
size_t i;
for (ALL_CELLS_IN_SHEET(sheet,i,cell))
{
if (cell && cell->clock_t2)
if (cell && cell->clock_requested)
{
cell->updated = false;
cell->clock_t0 = true;
cell->clock_t1 = true;
cell->clock_t2 = false;
cell->use_iter_cont = true;
cell->clock_resolving = true;
cell->clock_requested = false;
tfree(&(cell->tok[STYLE_VAL]));
}
}
@ -689,14 +692,33 @@ void update(Sheet *sheet)
upd_clock = true;
recompvalue(sheet, w);
}
bool current_changed = false;
for (ALL_CELLS_IN_SHEET(sheet,i,cell))
{
if (cell && cell->clock_t1)
if (cell && cell->clock_resolving)
{
tfree(&(cell->tok[CURR_VAL]));
cell->tok[CURR_VAL] = cell->tok[RES_VAL];;
cell->tok[RES_VAL].type = EMPTY;
cell->clock_t1 = false;
current_changed = true;
}
}
if (current_changed) {
/* Recompute all of the non-clocked cells so that they get the values
of the newly-changed clocked cells
*/
for (ALL_CELLS_IN_SHEET(sheet, i, cell)) {
if (cell) {
if (cell->clock_resolving) {
cell->clock_resolving = false;
} else {
cell->updated = false;
}
}
}
for (ALL_LOCS_IN_SHEET(sheet, w)) {
upd_clock = true;
recompvalue(sheet, w);
}
}
upd_clock = false;
@ -902,10 +924,11 @@ void clk(Sheet *sheet, const Location at)
{
assert(sheet != (Sheet*)0);
assert(IN_OCTANT(at));
assert(LOC_WITHIN(sheet,at));
if (CELL_AT(sheet,at))
assert(LOC_WITHIN(sheet, at));
Cell* toclock = CELL_AT(sheet, at);
if (iterable(toclock))
{
CELL_AT(sheet,at)->clock_t2 = true;
toclock->clock_requested = true;
sheet->clk = true;
}
}