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Rewrote Survey gotoExpression tests now that we have perl power in

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expressions
This commit is contained in:
Patrick Donelan 2009-04-02 01:54:21 +00:00
parent 3d70a213cc
commit 654f8d6b72
2 changed files with 51 additions and 98 deletions
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76
lib/WebGUI/Asset/Wobject/Survey/ResponseJSON.pm
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@ -649,58 +649,30 @@ indicates that we should branch.
The gotoExpression.
A gotoExpression is a string representing a list of expressions (one per line) of the form:
target: expression
target: expression
...
This subroutine iterates through the list, processing each line and, all things being
well, evaluates the expression. The first expression to evaluate to true triggers a
call to goto($target).
call to L<"processGoto">.
The expression is a simple subset of the formula language used in spreadsheet programs
such as Excel, OpenOffice, Google Docs etc..
The expression should be valid perl. Any section/question variables that you refer to
should be written as $var, as if your perl code had access to that variable. In reality,
those variables don't exist - they're substituted in via L<"parseGotoExpression"> and
then the expression is evaluated in a safe compartment.
Here is an example using section variables S1 and S2 as jump targets and question
variables Q1-3 in the expression. It jumps to S1 if the user's answer to Q1 has a value
of 3, jumps to S2 if Q2 + Q3 < 10, and otherwise doesn't branch at all (the default).
S1: Q1 = 3
S2: Q2 + Q3 < 10
Arguments are evaluated as follows:
S1: $Q1 == 3
S2: $Q2 + $Q3 < 10
Numeric arguments evaluate as numbers
=over 4
=item * No support for strings (and hence no string matching)
=item * Question variable names (e.g. Q1) evaluate to the numeric value associated with
user's answer to that question, or undefined if the user has not answered that question
=back
Binary comparisons operators: = != < <= >= >
=over 4
=item * return boolean values based on perl's equivalent numeric comparison operators
=back
Simple math operators: + - * /
=over 4
=item * return numeric values
=back
Later we may add Boolean operators: AND( x; y; z; ... ), OR( x; y; z; ... ), NOT( x ), with args separated by
semicolons (presumably because spreadsheet formulas use commas to indicate cell ranges)
Later still you may be able to say AVG(section1) or SUM(section3) and have those functions automatically
compute their result over the set of all questions in the given section.
But for now those things can be done manually using the limited subset defined.
You can do advanced branching by creating your own variables within the expression, for
example, to branch when the average of 3 questions is greater than 5:
S1: $avg = ($Q1 + $Q2 + $Q3) / 3; $avg > 5
=cut
@ -793,12 +765,7 @@ Uses the following simple strategy:
First, parse the expression as:
target: expression
Replace each questionName with its response value (from the $responses hashref)
Massage the expression into valid perl
Check that only valid tokens remain. This last step ensures that any invalid questionNames in
the expression generate an error because our list of valid tokens doesn't include a-z
Replace each "$questionName" with its response value (from the $responses hashref)
=cut
@ -808,9 +775,6 @@ sub parseGotoExpression {
$self->session->log->debug("Parsing gotoExpression: $expression");
# Valid gotoExpression tokens are..
my $tokens = qr{\s|[-0-9=!<>+*/.()&|:?]};
my ( $target, $rest ) = $expression =~ /\s* ([^:]+?) \s* : \s* (.*)/x;
$self->session->log->debug("Parsed as Target: [$target], Expression: [$rest]");
@ -825,21 +789,9 @@ sub parseGotoExpression {
return;
}
# convert 'and' and 'or' to '&&' and '||'
$rest =~ s/\band\b/&&/ig;
$rest =~ s/\bor\b/||/ig;
# Replace each questionName with its response value
# Replace each "$questionName" with its response value
while ( my ( $questionName, $response ) = each %{$responses} ) {
$rest =~ s/$questionName/$response/g;
}
# convert '=' to '==' but don't touch '!=', '<=' or '>='
$rest =~ s/(?<![!<>])=(?!=)/==/g;
if ( $rest !~ /^$tokens+$/ ) {
$self->session->log->warn("Contains invalid tokens: $rest");
return;
$rest =~ s/\$$questionName/$response/g;
}
$self->session->log->debug("Processed as: $rest");