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Commit a7e1e09b authored by Reinhold Kainhofer's avatar Reinhold Kainhofer
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Implement functions and unary operators 

The shunting yard algorithm had to be severely extended (by using a temporary operand stack for the function arguments, and by storing the type of the previous token to distinguish unary operators from binary)
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language/de-DE/de-DE.plg_vmshipment_rules_shipping.ini
+ 1
− 0
View file @ a7e1e09b
......@@ -37,6 +37,7 @@ VMSHIPMENT_RULES_UNKNOWN_VARIABLE="Unknown variable '%s' in rule '%s'"
VMSHIPMENT_RULES_UNKNOWN_OPERATOR="Unknown operator '%s' in shipment rule '%s'"
VMSHIPMENT_RULES_PARSE_MISSING_PAREN="Error during parsing expression '%s': Opening parenthesis cannot be found!"
VMSHIPMENT_RULES_PARSE_PAREN_NOT_CLOSED="Error during parsing expression '%s': A parenthesis was not closed properly!"
VMSHIPMENT_RULES_PARSE_FUNCTION_NOT_CLOSED="Error during parsing expression '%s': A function call was not closed properly!"
VMSHIPMENT_RULES_EVALUATE_NONNUMERIC="Encountered term '%s' during evaluation, that does not evaluate to a numeric value! (Full rule: '%s')"
VMSHIPMENT_RULES_EVALUATE_SYNTAXERROR="Syntax error during evaluation, RPN is not well formed! (Full rule: '%s')"
......
language/en-GB/en-GB.plg_vmshipment_rules_shipping.ini
+ 2
− 0
View file @ a7e1e09b
......@@ -40,10 +40,12 @@ VMSHIPMENT_RULES_UNKNOWN_VARIABLE="Unknown variable '%s' in rule '%s'"
VMSHIPMENT_RULES_UNKNOWN_OPERATOR="Unknown operator '%s' in shipment rule '%s'"
VMSHIPMENT_RULES_PARSE_MISSING_PAREN="Error during parsing expression '%s': Opening parenthesis cannot be found!"
VMSHIPMENT_RULES_PARSE_PAREN_NOT_CLOSED="Error during parsing expression '%s': A parenthesis was not closed properly!"
VMSHIPMENT_RULES_PARSE_FUNCTION_NOT_CLOSED="Error during parsing expression '%s': A function call was not closed properly!"
VMSHIPMENT_RULES_EVALUATE_NONNUMERIC="Encountered term '%s' during evaluation, that does not evaluate to a numeric value! (Full rule: '%s')"
VMSHIPMENT_RULES_EVALUATE_SYNTAXERROR="Syntax error during evaluation, RPN is not well formed! (Full rule: '%s')"
VMSHIPMENT_RULES_EVALUATE_UNKNOWN_OPERATOR="Unknown operator '%s' encountered during evaluation of rule '%s'."
VMSHIPMENT_RULES_EVALUATE_UNKNOWN_FUNCTION="Unknown function '%s' encountered during evaluation of rule '%s'."
VMSHIPMENT_RULES_EVALUATE_UNKNOWN_ERROR="Unknown error occurred during evaluation of rule '%s'."
VMSHIPMENT_RULES_EVALUATE_ASSIGNMENT_TOPLEVEL="Assignments are not allows inside expressions (rule given was '%s')"
VMSHIPMENT_RULES_EVALUATE_UNKNOWN_VALUE="Evaluation yields unknown value while evaluating rule part '%s'."
\ No newline at end of file
rules_shipping_advanced.php
+ 177
− 44
View file @ a7e1e09b
......@@ -28,6 +28,26 @@ if (!class_exists ('plgVmShipmentRules_Shipping_Base')) {
require (dirname(__FILE__).DS.'rules_shipping_base.php');
}
function print_array($obj) {
$res = "";
if (is_array($obj)) {
$res .= "array(";
$sep = "";
foreach ($obj as $e) {
$res .= $sep . print_array($e);
$sep = ", ";
}
$res .= ")";
} elseif (is_string($obj)) {
$res .= "\"$obj\"";
} else {
$res .= (string)$obj;
}
return $res;
}
/** Shipping costs according to general rules.
* Derived from the standard plugin, no need to change anything! The standard plugin already uses the advanced rules class defined below, if it can be found
*/
......@@ -85,6 +105,7 @@ class plgVmShipmentRules_Shipping_Advanced extends plgVmShipmentRules_Shipping_B
*/
class ShippingRule_Advanced extends ShippingRule {
var $operators = array(
".-" => 100, ".+" => 100,
"^" => 70,
"*" => 60, "/" => 60, "%" => 60,
"+" => 50, "-" => 50,
......@@ -94,7 +115,11 @@ class ShippingRule_Advanced extends ShippingRule {
" OR " => 20, "OR" => 20,
"=" => 10,
"(" => 0, ")" =>0 );
"(" => 0, ")" =>0
);
var $unary_ops = array(
"-" => ".-", "+" => ".+"
);
function __construct ($rule, $countries, $tax_id) {
parent::__construct ($rule, $countries, $tax_id);
......@@ -105,7 +130,7 @@ class ShippingRule_Advanced extends ShippingRule {
$str_re = '/("[^"]*"|\'[^\']*\')/';
$strings = preg_split($str_re, $expression, -1, PREG_SPLIT_DELIM_CAPTURE|PREG_SPLIT_NO_EMPTY);
// Then split all other parts of the expression at the operators
$op_re = ':\s*( OR |&&| AND |<=|=>|>=|=>|<>|!=|==|<|=|>|~|\+|-|\*|/|%|\(|\)|\^)\s*:';
$op_re = ':\s*( OR |&&| AND |<=|=>|>=|=>|<>|!=|==|<|=|>|~|\+|-|\*|/|%|\(|\)|\^|,)\s*:';
$atoms = array();
foreach ($strings as $s) {
if (preg_match($str_re, $s)) {
......@@ -115,30 +140,13 @@ class ShippingRule_Advanced extends ShippingRule {
$atoms = array_merge ($atoms, $newatoms);
}
}
// Finally handle the double meaning of -: After an operator and before an operand, it is NOT an operator, but belongs to the operand
$prevop = true;
$result = array();
$leftover = '';
foreach ($atoms as $a) {
if ($a == "-") {
$prev = end($result);
if (is_null ($prev) || (preg_match ($op_re, $prev) && $prev != ')')) {
$leftover = $a;
} else {
$result[] = $leftover.$a;
$leftover = '';
}
} else {
$result[] = $leftover.$a;
$leftover = '';
}
}
return $result;
return $atoms;
}
/** parse the mathematical expressions (following Knuth 1962):
/** parse the mathematical expressions using the Shunting Yard Algorithm by Dijkstra (with some extensions to allow arbitrary functions):
* First parse the string into an array of tokens (operators and operands) by a simple regexp with known operators as separators)
* TODO: Update this description to include unary operators and general function calls
* Then convert the infix notation into postfix (RPN), taking care of operator precedence
* 1) Initialize empty stack and empty result variable
* 2) Read infix expression from left to right, one atom at a time
......@@ -153,7 +161,10 @@ class ShippingRule_Advanced extends ShippingRule {
* 6b) push them to the result (not the opening parenthesis, of course)
* 7) At the end of the input, pop all operators from the stack and onto the result
*
* Afterwards, convert this RPN list into an expression tree to be evaluate
* Afterwards, convert this RPN list into an expression tree to be evaluated
*
* For the full algorithm, including function parsing, see Wikipedia:
* http://en.wikipedia.org/wiki/Shunting_yard_algorithm
*
*/
function parseRulePart($rulepart) {
......@@ -180,32 +191,104 @@ class ShippingRule_Advanced extends ShippingRule {
$is_assignment = false;
$stack = array (); // 1)
$rpn = array ();
$prev_token_operator = false;
$function_args = array();
$out_stack = array();
foreach ($atoms as $a) { // 2)
if (!isset($this->operators[$a])) { // 3) Operand
array_push ($rpn, $a);
} elseif ($a == "(") { // 5) parenthesis
array_push ($stack, $a);
if ($a == ",") { // A function argument separator
// pop-and-apply all operators back to the left function paren
while (count($stack)>0) { // 4a)
$op = array_pop ($stack);
if ($op != "FUNCTION(") {
array_push ($out_stack, $op);
} else {
// No unary operator -> add it back to stack, exit loop
array_push ($stack, $op);
break;
}
} while (0);
$this_func = array_pop($function_args);
// Add current output stack as argument, reset temporary output stack
if (!empty($out_stack)) $this_func[] = $out_stack;
$function_args[] = $this_func;
$out_stack = array();
$prev_token_operator = true;
} elseif ($a == "(" and !$prev_token_operator) { // 5) parenthesis after operand -> FUNCTION CALL
array_push ($stack, "FUNCTION(");
// retrieve function name from RPN list (remove last entry from operand stack!)
$function = array_pop ($out_stack);
$new_stack = array();
// Set up function call data structure on function_args stack:
$function_args[] = array(/* old operand stack: */$out_stack, $function);
// Use a the temporary operand stack until the closing paren restores the previous operand stack again
$out_stack = array();
$prev_token_operator = true;
} elseif ($a == "(" and $prev_token_operator) { // 5) real parenthesis
$stack[] = $a;
$prev_token_operator = true;
} elseif ($a == ")") { // 6) parenthesis
do {
$op=array_pop($stack); // 6a)
if (!is_null($op) && ($op != "(")) {
array_push ($rpn, $op); // 6b)
} else {
if ($op != "(") {
// If no ( can be found, the expression is wrong!
JFactory::getApplication()->enqueueMessage(JText::sprintf('VMSHIPMENT_RULES_PARSE_MISSING_PAREN', $rulepart), 'error');
if ($op == "(") {
break; // We have found the opening parenthesis
} elseif ($op =="FUNCTION(") { // Function call
// Remove function info from the functions stack; Format is array(PREVIOUS_OPERAND_STACK, FUNCTION, ARGS...)
$this_func = array_pop ($function_args);
// Append last argument (if not empty)
if (!empty($out_stack)) $this_func[] = $out_stack;
// restore old output/operand stack
$out_stack = array_shift($this_func);
// Function name is the next entry
$function = array_shift($this_func);
// All other entries are function arguments, so append them to the current operand stack
foreach ($this_func as $a) {
foreach ($a as $aa) {
$out_stack[] = $aa;
}
}
$out_stack[] = array("FUNCTION", $function, count($this_func));
break; // We have found the opening parenthesis
} elseif (!is_null($op)) {
$out_stack[]=$op; // 6b) "normal" operators
} else {
// no ( and no operator, so the expression is wrong!
JFactory::getApplication()->enqueueMessage(JText::sprintf('VMSHIPMENT_RULES_PARSE_MISSING_PAREN', $rulepart), 'error');
break;
}
} while (true);
} else { // 4) operators
// For operators, pop operators from the stack until you reach an opening parenthesis,
$prev_token_operator = false;
} elseif (isset($this->unary_ops[$a]) && $prev_token_operator) { // 4) UNARY operators
// Unary and binary operators need to be handled differently:
// Unary operators must only pop other unary operators, never any binary operator
$unary_op = $this->unary_ops[$a];
// For unary operators, pop other unary operators from the stack until you reach an opening parenthesis,
// an operator of lower precedence, or a right associative symbol of equal precedence.
while (count($stack)>0) { // 4a)
$op = array_pop ($stack);
// Remove all other unary operators:
if (in_array ($op, $this->unary_ops)) {
array_push ($out_stack, $op);
} else {
// No unary operator -> add it back to stack, exit loop
array_push ($stack, $op);
break;
}
} while (0);
array_push ($stack, $unary_op); // 4b)
$prev_token_operator = true;
} elseif (isset($this->operators[$a])) { // 4) BINARY operators
$prec = $this->operators[$a];
$is_condition |= in_array($a, $condition_ops);
$is_assignment |= ($a == "=");
// For operators, pop operators from the stack until you reach an opening parenthesis,
// an operator of lower precedence, or a right associative symbol of equal precedence.
while (count($stack)>0) { // 4a)
$op = array_pop ($stack);
// The only right-associative operator is =, which we allow at most once!
......@@ -218,10 +301,15 @@ class ShippingRule_Advanced extends ShippingRule {
array_push ($stack, $op); // 4b)
break;
} else {
array_push ($rpn, $op);
array_push ($out_stack, $op);
}
} while (0);
array_push ($stack, $a); // 4b)
$prev_token_operator = true;
} else { // 3) Everything else is an Operand
$out_stack[] = $a;
$prev_token_operator = false;
}
}
// Finally, pop all operators from the stack and append them to the result
......@@ -230,11 +318,15 @@ class ShippingRule_Advanced extends ShippingRule {
if ($op == "(") {
JFactory::getApplication()->enqueueMessage(JText::sprintf('VMSHIPMENT_RULES_PARSE_PAREN_NOT_CLOSED', $rulepart), 'error');
} else {
array_push ($rpn, $op);
array_push ($out_stack, $op);
}
}
if (!empty($function_args)) {
JFactory::getApplication()->enqueueMessage(JText::sprintf('VMSHIPMENT_RULES_PARSE_FUNCTION_NOT_CLOSED', $rulepart), 'error');
}
/** Now, turn the RPN into an expression tree (i.e. "evaluate" it into a tree structure, according to Knuth:
/** Now, turn the RPN into an expression tree (i.e. "evaluate" it into a tree structure), according to Knuth:
* 1) Initialize an empty stack
* 2) Read the RPN from left to right
* 3) If operand, push it onto the stack
......@@ -248,11 +340,31 @@ class ShippingRule_Advanced extends ShippingRule {
*/
$stack=array(); // 1)
foreach ($rpn as $e) { // 2)
if (!isset($this->operators[$e])) { // 3)
// Operand => push onto stack
array_push ($stack, $e);
} else { // 4)
foreach ($out_stack as $e) { // 2)
if (is_array($e) && $e[0]=="FUNCTION") { // A function call (#args is saved as $e[2], so remove that number of operands from the stack)
$function = $e[1];
$argc = $e[2];
$args = array();
for ($i = $argc; $i > 0; $i--) {
$a = array_pop($stack);
array_unshift($args, $a);
}
array_unshift($args, $function);
array_unshift($args, "FUNCTION");
$stack[] = $args;
} elseif (in_array($e, $this->unary_ops)) { // 4) unary operators
// Operator => apply to the last value on the stack
if (count($stack)<1) { // 4d)
JFactory::getApplication()->enqueueMessage(JText::sprintf('VMSHIPMENT_RULES_EVALUATE_SYNTAXERROR', $rulepart), 'error');
array_push($stack, 0);
continue;
}
$o1 = array_pop($stack);
// Special-case chained comparisons: if e is a comparison, and operator(o1) is also a comparison,
// insert the arguments to the existing comparison instead of creating a new one
$op = array ($e, $o1); // 4b)
array_push ($stack, $op); // 4c)
} elseif (isset($this->operators[$e])) { // 4) binary operators
// Operator => apply to the last two values on the stack
if (count($stack)<2) { // 4d)
JFactory::getApplication()->enqueueMessage(JText::sprintf('VMSHIPMENT_RULES_EVALUATE_SYNTAXERROR', $rulepart), 'error');
......@@ -276,7 +388,11 @@ class ShippingRule_Advanced extends ShippingRule {
$op = array ($e, $o1, $o2); // 4b)
}
array_push ($stack, $op); // 4c)
} else { // 3)
// Operand => push onto stack
array_push ($stack, $e);
}
}
// 5a)
if (count($stack) != 1) {
......@@ -307,3 +423,20 @@ class ShippingRule_Advanced extends ShippingRule {
}
// No closing tag
/*$rule = new ShippingRule_Advanced("", array(), 0);
$rp="a+b+(-1+d)";
$rp="1+maxx(a,b)";
$rp="f(1,2,+)";
$rp="1+year()";
$rp = "1+max( 1,2,3,4,5) + min(9,10,101)";
$rp = "abs(0-1.9999)";
$rp="max(1,min(0,5,7), 9)";
// $rp="f()";
print_r($rule->tokenize_expression($rp));
$rule->parseRulePart($rp);
print_r($rule->conditions);
print_r($rule->shipping);
print_r($rule->evaluateTerm($rule->shipping, array()));
*/
\ No newline at end of file
rules_shipping_base.php
+ 49
− 6
View file @ a7e1e09b
......@@ -704,6 +704,40 @@ class ShippingRule {
return true;
}
function evaluateFunction ($function, $args) {
$func = strtolower($function);
// Functions with no argument:
if (count($args) == 0) {
switch ($func) {
case "second": return getdate()["seconds"]; break;
case "minute": return getdate()["minutes"]; break;
case "hour": return getdate()["hours"]; break;
case "day": return getdate()["mday"]; break;
case "weekday":return getdate()["wday"]; break;
case "month": return getdate()["mon"]; break;
case "year": return getdate()["year"]; break;
case "yearday":return getdate()["yday"]; break;
}
}
// Functions with exactly one argument:
if (count($args) == 1) {
switch ($func) {
case "round": return round($args[0]); break;
case "ceil": return ceil ($args[0]); break;
case "floor": return floor($args[0]); break;
case "abs": return abs($args[0]); break;
}
}
// Functions with variable number of args
switch ($func) {
case "max": return max($args); break;
case "min": return min($args); break;
}
// No known function matches => print an error, return 0
JFactory::getApplication()->enqueueMessage(JText::sprintf('VMSHIPMENT_RULES_EVALUATE_UNKNOWN_FUNCTION', $function, $this->rulestring), 'error');
return 0;
}
function evaluateTerm ($expr, $vals) {
if (is_null($expr)) {
return $expr;
......@@ -724,17 +758,24 @@ class ShippingRule {
$op = array_shift($expr);
$args = array();
$evaluate = true;
if ($op == "FUNCTION") {
$evaluate = false;
}
foreach ($expr as $e) {
$term = $evaluate ? ($this->evaluateTerm($e, $vals)) : $e;
if ($op == 'comparison') {
// For comparisons, we only evaluate every other term (the operators are NOT evaluated!)
$evaluate = !$evaluate;
}
if ($op == "FUNCTION") {
$evaluate = true;
}
if (is_null($term)) return null;
$args[] = $term;
}
$res = false;
switch ($op) {
// Logical operators:
case 'OR':
case ' OR ': foreach ($args as $a) { $res = ($res || $a); }; break;
case '&&':
......@@ -742,6 +783,7 @@ class ShippingRule {
case ' AND ': $res = true; foreach ($args as $a) { $res = ($res && $a); }; break;
case 'in': $needle = array_shift($args); $res = in_array($needle, $args); break;
// Comparisons:
case '<':
case '<=':
case '=<':
......@@ -756,6 +798,11 @@ class ShippingRule {
case 'comparison':
$res = $this->evaluateComparison($args, $vals); break;
// Unary operators:
case '.-': $res = -$args[0]; break;
case '.+': $res = $args[0]; break;
// Binary operators
case "+": $res = ($args[0] + $args[1]); break;
case "-": $res = ($args[0] - $args[1]); break;
case "*": $res = ($args[0] * $args[1]); break;
......@@ -763,12 +810,8 @@ class ShippingRule {
case "%": $res = (fmod($args[0], $args[1])); break;
case "^": $res = ($args[0] ^ $args[1]); break;
# TODO: Document these functions:
case "round": $res = round($args[0]); break;
case "ceil": $res = ceil($args[0]); break;
case "floor": $res = floor($args[0]); break;
case "max": $res = max($args); break;
case "min": $res = min($args); break;
// Functions:
case "FUNCTION": $func = array_shift($args); $res = $this->evaluateFunction($func, $args); break;
default: $res = false;
}
......
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