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Decision tables: Difference between revisions
usable code object in javascript
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=={{header|JavaScript}}==
===Interactive===
Since this is an interactive web page, results can't be listed. See http://jsfiddle.net/rGP6C/1/ for a live demo.
<lang javascript><html>
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</script>
</html></lang>
===DecTab object===
This implements a DecisionTable object called <code>DecTab</code>. The JavaScript dialect is Microsoft's JScript.
<lang javascript>
var DecTab = function () {
this.conditions = [];
this.rules = [];
this.actions = [];
}
DecTab.prototype.Conditions = function () {
var args = [].slice.call(arguments);
for (var i = 0; i < args.length; i++) {
this.conditions.push(args[i]);
}
return this;
};
DecTab.prototype.RulesActions = function (rules, actions) {
var count = 0;
var actionable;
this.rules.push(rules)
this.actions.push(actions);
return this;
};
DecTab.prototype.Decide = function () {
var decision = [];
var decided = false;
for (var i = 0; i < this.conditions.length; i++) {
decision.push((this.conditions[i]()));
}
var decisionstring = "." + decision.join(".") + ".";
for (i = 0; i < this.rules.length; i++) {
var rule = [];
for (var j = 0; j < this.rules[i].length; j++) {
rule.push((this.rules[i][j]));
}
var rulestring = "." + rule.join(".") + ".";
if (rulestring === decisionstring) {
decided = true;
for (var k = 0; k < this.actions[i].length; k++) {
this.actions[i][k]();
}
break;
}
}
if (!decided) {
WScript.Echo("No decision table rows matched.");
}
}
</lang>
The task is rendered as follows
<lang javascript>
function Ask(q) {
WScript.StdOut.Write(q);
WScript.StdOut.Write(" [Y/N]?");
var ans = WScript.StdIn.ReadLine();
ans = ans.substr(0, 1).toUpperCase() === "Y" ? "Y" : "N";
return ans;
}
function Tell(w) {
WScript.Echo(w);
}
function Check_the_power_cable() {
Tell("Check the power cable.");
}
function Check_the_printer_computer_cable() {
Tell("Check the printer-computer cable.");
}
function Ensure_printer_software_is_installed() {
Tell("Ensure printer software is installed.");
}
function Check_replace_ink() {
Tell("Check/replace ink.");
}
function Check_for_paper_jam() {
Tell("Check for paper jam.");
}
function Printer_Prints() {
return Ask("Printer prints");
}
function A_red_light_is_flashing() {
return Ask("A red light is flashing");
}
function Printer_is_recognized_by_computer() {
return Ask("Printer is recognized by computer");
}
var DT = new DecTab()
.Conditions(
Printer_Prints,
A_red_light_is_flashing,
Printer_is_recognized_by_computer)
.RulesActions(["N", "Y", "N"], [Check_the_printer_computer_cable, Ensure_printer_software_is_installed, Check_replace_ink])
.RulesActions(["N", "Y", "Y"], [Check_replace_ink, Check_for_paper_jam])
.RulesActions(["N", "N", "N"], [Check_the_power_cable, Check_the_printer_computer_cable, Ensure_printer_software_is_installed])
.RulesActions(["N", "N", "Y"], [Check_for_paper_jam])
.RulesActions(["Y", "Y", "N"], [Ensure_printer_software_is_installed, Check_replace_ink])
.RulesActions(["Y", "Y", "Y"], [Check_replace_ink])
.RulesActions(["Y", "N", "N"], [Ensure_printer_software_is_installed])
.RulesActions(["Y", "N", "Y"], [])
.Decide();
</lang>
And a sample run
<lang text>
C:\>CScript DecisionTable.js
Printer prints [Y/N]?Y
A red light is flashing [Y/N]?Y
Printer is recognized by computer [Y/N]?Y
Check/replace ink.
</lang>
=={{header|Perl 6}}==
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