I need to be able to have several possible values under the same key in a mapping. Today, Solidity's mappings are mono-valued: writing a value overwrite the previous one (which is still in the blockchain, but not retrievable by a contract). I wrote this code to have multi-valued mappings:
contract MVM {
struct Bucket {
bool exists;
uint num; // Never decreases: we can only add records, not remove them.
mapping(uint => Record) records;
}
struct Record {
bool exists;
string info;
}
// Do not make it public: the compiler crashes when generating
// accessors https://github.com/ethereum/solidity/issues/633
mapping(string => Bucket) data;
function set(string key, string value) {
if (data[key].exists) {
data[key].records[data[key].num] = Record(true, value);
}
else {
data[key].exists = true;
data[key].records[0] = Record(true, value);
}
data[key].num++;
}
function num_of(string key) returns (uint) {
return data[key].num; // Guaranteed to be initialized as zero?
}
function get(string key, uint index) returns (string) {
if (!data[key].exists || !data[key].records[index].exists) {
throw;
}
return data[key].records[index].info;
}
}
An example of its use from the geth console:
> mvs.set.sendTransaction("foo", "bar", {from:eth.accounts[0], gas: 1000000})
"0x79c52c437a94f3301775acec5639404eff563fce1a99ad097f5db28f109d7ab5"
> mvm.set.sendTransaction("foo", "thing", {from:eth.accounts[0], gas: 1000000})
"0xb26b8d34691b0da5cb48af68933e81b514199f4ed8bd2b557767c8b55da85f50"
> mvm.get.call("foo")
"bar"
> mvm.get.call("foo", 1)
"thing"
> mvm.num_of.call("foo")
2
Is there a flaw in my approach? Or a better solution?
contract MVM {
struct Record {
bool exists;
string info;
}
mapping(string => Record[]) data;
// If you want to iterate the whole thing, you can use this:
string[] keysNames;
function set(string key, string value) {
// Remove this if, if you don't need iteration
if (data[key].length == 0) {
keysNames.push(key);
}
data[key].push(Record(true, value));
}
function num_of(string key) constant returns (uint) {
return data[key].length;
}
function get(string key, uint index) constant returns (string) {
if (data[key][index].exists == false) {
throw;
}
return data[key][index].info;
}
function exampleIterate() constant returns (string last) {
uint keysLen = keysNames.length;
for(uint i = 0; i < keysLen; i++) {
uint recordsLen = data[keysNames[i]].length;
for(uint j = 0; j < recordsLen; j++) {
last = data[keysNames[i]][j].info;
}
}
}
}
Related
I started coding a validation of my Excel Sheet. I implemented quite a bit so I try to keep the code short.
My source code:
function main(workbook: ExcelScript.Workbook) {
console.log("starting...");
let cs = createVariantCategorySheet(workbook.getWorksheet("variant categories"));
cs.validateSheet();
for (let m of cs.logMessages) {
console.log(m);
}
console.log("finished...");
}
function createVariantCategorySheet(worksheet: ExcelScript.Worksheet): ImportSheet {
let sheet = new ImportSheetBuilder()
.name("variant categories")
.index(1)
.worksheet(worksheet)
.addColumnInfo(
new ColumnInfoBuilder()
.index(4)
.name("Sort Order")
// .addChecker(new NotEmptyChecker())
.addChecker(new UniqueSortOrderChecker(worksheet, worksheet.getRange("B:B")))
.build()
)
.build();
return sheet;
}
class ImportSheet {
public name: string;
public index: number;
public worksheet?: ExcelScript.Worksheet
columns: ColumnInfo[];
public logMessages: string[];
constructor() {
this.index = -1;
this.name = "";
this.columns = [];
this.logMessages = [];
}
// ... Some usefull private methods ...
validateSheet() {
let rowCount = this.getRowCount();
for (let rowIndex = 1; rowIndex < rowCount; rowIndex++) {
if (this.isRowEmpty(rowIndex)) {
this.logMessages.push("no more lines... ")
return;
}
this.validatingRow(rowIndex);
}
}
private validatingRow(rowIndex: number) {
this.logMessages.push("iterating over line [" + rowIndex + "]")
for (let columnItem of this.columns) {
this.validatingColumn(columnItem, this.rangeToValidate(rowIndex, columnItem.index));
}
}
private validatingColumn(columnItem: ColumnInfo, rangeToValidate: ExcelScript.Range){
for (let validator of columnItem.validator) {
let stringToValidate = rangeToValidate.getValue().toString();
this.logMessages.push("###### " + validator.isValid)
if (!validator.isValid(stringToValidate, rangeToValidate.getRowIndex())) {
this.logMessages.push("## ## ERROR: Failed Validation " + validator.getName() +
" in '" + rangeToValidate.getAddress() + "' for column '" +
columnItem.name + "'.");
} else {
this.logMessages.push("## ## INFO: Success Validation " + validator.getName() +
" in '" + rangeToValidate.getAddress() + "' for column '" +
columnItem.name + "'.");
}
}
}
}
class ColumnInfo {
name: string;
index: number;
validator: Checker[];
}
interface Checker {
isValid(value: string, rowIndex: number): boolean
getName(): string
}
class NotEmptyChecker implements Checker {
isValid(value: string): boolean {
if (value)
return true;
else
return false;
}
getName(): string {
return NotEmptyChecker.name;
}
}
class UniqueSortOrderChecker implements Checker {
sortOrderMap: Map<string, Set<string>>;
range: ExcelScript.Range
worksheet: ExcelScript.Worksheet
constructor(worksheet: ExcelScript.Worksheet, range: ExcelScript.Range) {
this.range = range;
this.worksheet = worksheet;
this.sortOrderMap = new Map<string, Set<string>>();
}
isValid(value: string, rowIndex: number): boolean {
return true;
}
getName(): string {
return UniqueSortOrderChecker.name;
}
}
I left out the Builders as they just create the objects.
The above code works and validates the file like I wish.
The generated code for the Method UniqueSortOrderChecker.isValid looks like:
function (value, rowIndex) {
ExcelScript.engine.traceLine(undefined);
return true;
}
So the interesting part is, once I change the UniqueSortOrderChecker into:
isValid(value: string, rowIndex: number): boolean {
console.log("test");
return true;
}
The generated code looks now totally different and returns a promise:
function (value, rowIndex) {
return __awaiter(this, void 0, void 0, function () {
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
ExcelScript.engine.traceLine(264);
return [4 /*yield*/, console.log("test")];
case 1:
(_a.sent());
ExcelScript.engine.traceLine(undefined);
return [2 /*return*/, true];
}
});
});
}
Same happens when I try to read cell value like:
isValid(value: string, rowIndex: number): boolean {
let cellValue = this.range.getRow(rowIndex).getValue().toString();
return true;
}
turns it into a promise return type like:
function (value, rowIndex) {
return __awaiter(this, void 0, void 0, function () {
var cellValue;
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
ExcelScript.engine.traceLine(264);
return [4 /*yield*/, this.range.getRow(rowIndex).getValue()];
case 1:
cellValue = (_a.sent()).toString();
ExcelScript.engine.traceLine(undefined);
return [2 /*return*/, true];
}
});
});
}
Can anyone help me out here? As once it is turned into a promise the return value is always true and my validation does not work.
Hope the question is not to long, but I wanted to give context.
Office Script relies on some complex logic underneath to give inherently asynchronous code the appearance of synchronous execution.
As of 2021-07-01 underneath the covers every Office Script method including console.log returns a promise. As you have discovered!
The complex logic applies awaits to these pieces of code to make them match the IntelliSense and appear synchronous.
The majority of common cases as of 2021-07-01 are covered by this logic, however there are some gaps in the complex transformation logic that may miss some scenarios.
Use of Office Script methods and console.log are not yet supported in class methods.
If you must use Office Script methods or console.log in classes today, you can mark these class methods as async and await them.
If this feature is important for your scenario I recommend sending feedback in the Office Script Editor click the ... and then click Send Feedback.
I want to create a programming language that has multiple functions and a single main function. For the interpreter of the language I am using a hash map, but I do not know how to store intermediate values in the hash map. An example of a valid program includes:
DEF MAIN { ADDITION(4) } ;
DEF ADDITION x { x+3 } ;
This is what I have so far:
HashMap<String, Function> Program() : {
HashMap<String, Function> symbolTable = new HashTable<>();
}
{
(FunctionDefinition(symbolTable))*
<EOF>
{return symbolTable;}
}
void FunctionDefinition(SymbolTable table)
{
Function f;
String name;
}
{
<DEF> <SPACE>
(
(name = <MAIN>)
| (name = <FUNC> (<SPACE> <PARAM> ))
<SPACE>
f = FunctionBody()
";"
{
if (table.hashKey(name)) { System.out.println("do something");}
else { table.add(name, f); }
})
}
void FunctionBody() : {}
{
<LEFT> <SPACE>
Expression()
<SPACE> <RIGHT>
}
void Expression() : {}
{
AdditiveExpression()
}
void AdditiveExpression() : {
}
{
MultiplicativeExpression() (<PLUS> MultiplicativeExpression()
{
try {
int a = s.pop();
int b = s.pop();
stack.push(a+b);
}
catch (ClassCastException ex) {
System.out.println("Only numbers can be used for arithmetic operations.");
throw new ParseException();
}
})*
}
void MultiplicativeExpression() : {
}
{
UnaryExpression() (<MUL> UnaryExpression()
{
try {
int a = s.pop();
int b = s.pop();
stack.push(a*b);
}
catch (ClassCastException ex) {
System.out.println("Only numbers can be used for arithmetic operations");
throw new ParseException();
}
})*
}
void UnaryExpression() : {
Token x;
}
{
(x = <NUMBER> | x = <PARAM>)
{s.push(x.image);}
}
Any help will be greatly appreciated.
As #Theodore has said, you can't execute the program while you're parsing it. I thought I'd add my two cents here.
The result of the parsing could be the table of functions though, and you would have a main method that would do something like this:
Parser parser = new Parser(System.in, "UTF-8");
Map<String, Function> table = parser.program();
Function main = table.get("MAIN");
if (main == null) {
System.out.println("Function MAIN doesn't exist");
} else {
int r = main.invoke(table);
System.out.println("Result: " + r);
}
I see a few weird things in your code:
Instead of using a token <SPACE> between each token, you'd be better off using the SKIP instruction:
SKIP : { " " | "\r" | "\n" | "\t" }
You're using three different tokens for the same thing: <MAIN>, <FUNC>, <PARAM>. They're all names, and you could define a token <NAME> as follows:
TOKEN: {
< NAME: <LETTER>(<LETTER>|<DIGIT>)* >
| < #LETTER: ["a"-"z", "A"-"Z", "_"] >
| < #DIGIT: ["0"-"9"] >
}
The rule for a function definition would then become:
<DEF> <NAME> ( <NAME> )* functionBody() ";"
note that a function can have zero or more parameters; function MAIN would have zero.
In your example, function MAIN contains a forward reference to the function ADDITION, meaning that while parsing the body of function MAIN you will find a call to a function ADDITION that is not yet in the symbol table. The ability to use forward reference is a nice feature for a programming language, but it complicates the implementation slightly.
If you're doing an interpreter, you have basically two options to deal with forward references: 1) do a second pass after the parsing to "fix" the forward references, 2) do the name resolution during run time. The second option is simpler but slower.
Note that the parameters of a function are always defined before they are used. They are only accessible within the body of a function. You can build a table for the parameter while parsing the head of the definition, and then pass that table to the method that parses the body of the function.
Example:
void functionDefinition(Map<String, Function> table): {
Expression body;
Function f;
String name;
String param;
int paramCount = 0;
Map<String,Parameter> params = new HashMap<String,Parameter>();
}
{
<DEF> name=<NAME>.image (
param=<NAME>.image {params.put(param, new Parameter(paramCount++));}
)*
body=functionBody(params)
{ f = new Function(paramCount, body); }
";"
{
if (table.containsKey(name)) {
System.out.println("Function " + name + "already exists");
} else {
table.put(name, f);
}
}
}
To evaluate the expression in a function body, you can use the interpreter pattern, where the elements of an expression are all an implementation of an Expression interface:
public interface Expression {
public int evaluate(Map<String,Function> table, int... parms);
}
Here parms are the actual parameters passed to the function being executed.
The following files are the sources of a very simple, functioning implementation of a very simple language based on your question. It can execute your example:
DEF MAIN { ADDITION(4) } ;
DEF ADDITION x { x+3 } ;
and it can also execute something like this:
DEF MAIN { ADDITION3(4) } ;
DEF ADDITION3 x { ADDITION(x,3) } ;
DEF ADDITION x y { x+y } ;
I hope it will help.
JavaCC file, parser.jj:
options {
STATIC = false;
IGNORE_CASE = false;
}
PARSER_BEGIN(Parser)
package org.tastefuljava.minilang;
import java.io.InputStream;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.Map;
import java.util.HashMap;
import java.util.List;
import java.util.ArrayList;
public class Parser {
public static void main(String[] args) {
try {
Parser parser = new Parser(System.in, "UTF-8");
Map<String, Function> table = parser.program();
int r = Expression.call("MAIN").evaluate(table);
System.out.println("Result: " + r);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
PARSER_END(Parser)
SKIP : { " " | "\r" | "\n" | "\t" }
TOKEN: {
< DEF: "DEF" >
| < NAME: <LETTER>(<LETTER>|<DIGIT>)* >
| < #LETTER: ["a"-"z", "A"-"Z", "_"] >
| < #DIGIT: ["0"-"9"] >
| < PLUS: "+" >
| < MUL: "*" >
| < LEFT: "{" >
| < RIGHT: "}" >
| < NUMBER: (<DIGIT>)+ >
}
Map<String, Function> program(): {
Map<String, Function> symbolTable = new HashMap<>();
}
{
(functionDefinition(symbolTable))*
{return symbolTable;}
}
void functionDefinition(Map<String, Function> table): {
Expression body;
Function f;
String name;
String param;
int paramCount = 0;
Map<String,Parameter> params = new HashMap<String,Parameter>();
}
{
<DEF> name=<NAME>.image (
param=<NAME>.image {params.put(param, new Parameter(paramCount++));}
)*
body=functionBody(params)
{ f = new Function(paramCount, body); }
";"
{
if (table.containsKey(name)) {
System.out.println("Function " + name + "already exists");
} else {
table.put(name, f);
}
}
}
Expression functionBody(Map<String,Parameter> params): {
Expression e;
}
{
<LEFT>
e=expression(params)
<RIGHT>
{
return e;
}
}
Expression expression(Map<String,Parameter> params): {
Expression e;
}
{
e=additiveExpression(params)
{
return e;
}
}
Expression additiveExpression(Map<String,Parameter> params): {
Expression e, f;
}
{
e=multiplicativeExpression(params)
(<PLUS> f=multiplicativeExpression(params) {
e = Expression.add(e,f);
})*
{
return e;
}
}
Expression multiplicativeExpression(Map<String,Parameter> params): {
Expression e, f;
}
{
e=unaryExpression(params) (<MUL> f=unaryExpression(params) {
e = Expression.mul(e,f);
})*
{
return e;
}
}
Expression unaryExpression(Map<String,Parameter> params): {
Expression e;
String s;
int n;
Expression[] parms;
}
{
(
n=number() {
e = Expression.number(n);
}
| s=<NAME>.image ( parms=parameterList(params) {
e = Expression.call(s, parms);
} | {
Parameter p = params.get(s);
if (p != null) {
e = Expression.param(p.index);
} else {
// no parameter found: assume it's a parameterless function
e = Expression.call(s);
}
})
)
{
return e;
}
}
int number(): {
String s;
}
{
s=<NUMBER>.image
{
return Integer.parseInt(s);
}
}
Expression[] parameterList(Map<String,Parameter> params): {
List<Expression> parms = new ArrayList<Expression>();
Expression p;
}
{
"("
(
p=expression(params) { parms.add(p); }
( "," p=expression(params){ parms.add(p); } )*
)?
")"
{
return parms.toArray(new Expression[parms.size()]);
}
}
Function class, Function.java:
package org.tastefuljava.minilang;
public class Function {
public final int paramCount;
public final Expression body;
public Function(int paramCount, Expression body) {
this.paramCount = paramCount;
this.body = body;
}
}
Parameter class, Parameter.java:
package org.tastefuljava.minilang;
public class Parameter {
public final int index;
public Parameter(int index) {
this.index = index;
}
}
Expression interface, Expression.java:
package org.tastefuljava.minilang;
import java.util.Map;
public interface Expression {
public int evaluate(Map<String,Function> table, int... parms);
public static Expression number(int x) {
return (table, parms) -> x;
}
public static Expression add(Expression a, Expression b) {
return (table, parms) ->
a.evaluate(table, parms) + b.evaluate(table, parms);
}
public static Expression mul(Expression a, Expression b) {
return (table, parms) ->
a.evaluate(table, parms) * b.evaluate(table, parms);
}
public static Expression call(String name, Expression... parms) {
return (table, oldParms) -> {
Function f = table.get(name);
if (f == null) {
System.out.println("Unknown function " + name);
return 0;
} else if (f.paramCount != parms.length) {
System.out.println("Wrong number of parameters for function "
+ name + ": expected " + f.paramCount
+ ", actual " + parms.length);
return 0;
}
int[] newParms = new int[parms.length];
for (int i = 0; i < parms.length; ++i) {
newParms[i] = parms[i].evaluate(table, oldParms);
}
return f.body.evaluate(table, newParms);
};
}
public static Expression param(int index) {
return (table, parms) -> parms[index];
}
}
You need your FunctionBody nonterminal to return the intermediate representation for the function.
The problem is that you don't have an intermediate representation. You are trying to do direct interpretation, i.e. you are executing the program at the same time that it is parsed. That's fine for simple interactive calculators like the one in this ancient tutorial. However, once you start dealing with loops and functions you really need to generate (and later execute) intermediate code. See this FAQ for why.
If you are are taking a course, ask your instructor what he or she or they would recommend for intermediate code.
If you don't have an instructor, my advice is to generate machine code for a stack machine, since you are already using a stack for execution. See, for example, my notes on generating machine code for a stack machine in a recursive descent parser, especially pages 14 to 20; I didn't use a parser generator for this, but that shouldn't matter. (I use ^ for sequence concatenation, so, for example, m := m^div just means add a div instruction to the end of the intermediate representation.)
Any book on compilers will also cover this sort of stuff.
Tom Copeland's book probably has lots more information and is JavaCC specific.
I want to use functions as keys in a Map like this:
var timers : Map<Void->Void, snow.api.Timer>;
But Haxe won't compile:
Abstract Map has no #:to function that accepts IMap<Void -> Void, snow.api.Timer>
Is there a way to do this ?
It's easy to write a custom implementation:
import haxe.Constraints;
class FunctionMap<K:Function,V> implements IMap<K,V> {
private var _keys : Array<K>;
private var _values : Array<V>;
public function new () {
_keys = [];
_values = [];
}
public function get(k:K):Null<V> {
var keyIndex = index(k);
if (keyIndex < 0) {
return null;
} else {
return _values[keyIndex];
}
}
public function set(k:K, v:V):Void {
var keyIndex = index(k);
if (keyIndex < 0) {
_keys.push(k);
_values.push(v);
} else {
_values[keyIndex] = v;
}
}
public function exists(k:K):Bool {
return index(k) >= 0;
}
public function remove(k:K):Bool {
var keyIndex = index(k);
if (keyIndex < 0) {
return false;
} else {
_keys.splice(keyIndex, 1);
_values.splice(keyIndex, 1);
return true;
}
}
public function keys():Iterator<K> {
return _keys.iterator();
}
public function iterator():Iterator<V> {
return _values
.iterator();
}
public function toString():String {
var s = new StringBuf();
s.add("{");
for( i in 0..._keys.length ) {
s.add('<function>');
s.add(" => ");
s.add(Std.string(_values[i]));
if( i < _keys.length - 1 )
s.add(", ");
}
s.add("}");
return s.toString();
}
private function index(key:K) : Int {
for (i in 0..._keys.length) {
if (Reflect.compareMethods(key, _keys[i])) {
return i;
}
}
return -1;
}}
http://try.haxe.org/#DdF31
I just tried this in try.haxe.org, and the compiler doesn't seem to like it, so I'm guessing the answer is "no."
You could get around this with some cleverness:
class Test {
static function main() {
var map:Map<VoidVoid,String>;
map = new Map<VoidVoid,String>();
var thing = {func:foo};
map.set(thing,"bar");
trace(map.get({func:foo})); //fails
trace(map.get(thing)); //succeeds;
}
static function foo():Void
{
}
}
typedef VoidVoid = {
var func:Void->Void;
}
But that's not an ideal solution because wrapping it in a typedef like that will make it fail if it's not the exact same instance, even if the value inside is the same.
I also tried making a Map<Dynamic,String> since you can stuff function references in those, but that didn't work either.
At this point I should ask, what problem are you trying to solve this way? Perhaps it could be better solved some other way.
I want to do a midlet application for save product with its bar code, product's name, product's description and price. Then it is going to be saved as it:
123123123-coca cola-soda-6.50
124512341-crystal coca-soda-7.00
well for this I have built this code:
public boolean ProductoAgregar(String dato) // add product
{
byte bytes[] = dato.getBytes();
try {
rs.addRecord(bytes, 0, bytes.length);
return true;
} catch (RecordStoreException ex) {
ex.printStackTrace();
return false;
}
}
public boolean ProductoModificar(String dato, int id) // update product
{
try
{
byte bytes[] = dato.getBytes();
rs.setRecord(id, bytes, 0, dato.length());
return true;
}
catch(Exception ex)
{
return false;
}
}
public boolean ProductoEliminar(int id)// delete product
{
try
{
rs.deleteRecord(id);
return true;
}
catch(Exception ex)
{
return false;
}
}
I don't have an idea for how to create the method for find a product (with a part of its name, or with its bar code) and what is going to return? maybe an array?
For example all products has write coca in its name (or in description) or
find a unique product with bar code.
(This is a class with I'll instance for use its methods)
you can try following code, by editing as per your usage. I am using below code for searching an item from RMS Data.
public boolean SearchRecord(String Rec, int pos )
{
String [] data = getRecordData();
Rec = Rec.substring(0,pos);
for ( int i = 0 ; i < data.length ; i++ )
{
data[i] = data[i].substring(0, pos );
if ( Rec.toString().trim().equals(data[i].toString().trim()) )
{
data = null; // System.gc();
return true;
}
}
data = null; // System.gc();
return false;
}
By Changing the value of "pos" variable you can achieve your goal.
I'm trying to find the easiest way to search a string for an array of possible strings. I know the easy way to do this for characters is to use myString.IndexOfAny(charArray). But how what if I'd like to search my string for strings and not just characters? Are there any .net tricks or methods that make this easier?
Basically, I'd like to do something like this:
string myName = "rahkim";
string[] names = new string[] {"joe","bob","chris"};
if(myName.IndexOfAny(names) >= 0)
{
//success code//
}
I know there are ways to do this with loops, etc. But I was hoping for something inherent in the framework.
You should define if you want to to find equal strings or search for a matching substring. Both ways are easy pre-LINQ and with LINQ.
string myName = "rahkim";
string[] names = new string[] { "joe", "bob", "chris" };
Equal Strings, LINQ
bool contains = names.Contains(myName);
Equal Strings, Pre-LINQ
bool contains = new List<string>(name).Contains(myName);
Substrings, LINQ
bool contains = names.Any(name => name.Contains(myName));
Substring, Pre-LINQ
bool contains = false;
foreach(string name in names)
if (name.Contains(myName))
contains = true;
If anyone else found this while trying to search for a .Net method like String.IndexOfAny(String[]), this is my solution:
C#
public int IndexOfAny(string test, string[] values)
{
int first = -1;
foreach (string item in values) {
int i = test.IndexOf(item);
if (i >= 0) {
if (first > 0) {
if (i < first) {
first = i;
}
} else {
first = i;
}
}
}
return first;
}
VB
Public Function IndexOfAny(test As String, values As String()) As Integer
Dim first As Integer = -1
For Each item As String In values
Dim i As Integer = test.IndexOf(item)
If i >= 0 Then
If first > 0 Then
If i < first Then
first = i
End If
Else
first = i
End If
End If
Next
Return first
End Function
You can do a LastIndexOfAny(String[]) by just switching the
i < first
to
i > first
You can (also) use the static IndexOf method of the Array class:
bool hasName = Array.IndexOf(names, myName) > -1;
int IndexOfAny(String[] rgs) would indeed be nice but it's nominally an O(n^2) operation. If, in your application, the set of strings rgs is large and always the same, the most efficient approach is to load them into a trie data structure once, and then use the trie repeatedly to search for them within the unknown strings given at runtime.
Here is the relevant code, adapted from a C# trie source I found on the web, attributed to "Kerry D. Wong." In my version, each string in the trie has a "payload" of generic type TValue. To use this trie to simply search for substrings, the payload could always be set to true, as illustrated with simple_trie.
The other thing I changed here is that this trie automatically adapts allow for storage of arbitrary Unicode strings. The array at each node—which characterizes a trie—adjusts its base and length to accomodate the range of Unicode characters which need to be stored at that node. This allows for case-sensitive matching, for example.
The C# 3.0 initialization syntax is handy for this trie, but enabling it requires a dummy implementation of IEnumerable in order to compile. The CLR doesn't seem to call GetEnumerator() and I suggest that you don't try to enumerate with its result either.
using System;
using System.Collections.Generic;
using System.Linq; // only used in Main()
class Program
{
// trie with payload of type <String>
static Trie<String> value_trie = new Trie<String>
{
{ "rabbit", "cute" },
{ "giraffe", "tall" },
{ "ape", "smart" },
{ "hippo", "large" },
};
// degenerate case of a trie without payload
static Trie<bool> simple_trie = new Trie<bool>
{
{ "rabbit", true },
{ "giraffe", true },
{ "ape", true },
{ "hippo", true },
};
static void Main(String[] args)
{
String s = "Once upon a time, a rabbit met an ape in the woods.";
// Retrieve payloads for words in the string.
//
// output:
// cute
// smart
foreach (String word in value_trie.AllSubstringValues(s))
Console.WriteLine(word);
// Simply test a string for any of the words in the trie.
// Note that the Any() operator ensures that the input is no longer
// traversed once a single result is found.
//
// output:
// True
Console.WriteLine(simple_trie.AllSubstringValues(s).Any(e=>e));
s = "Four score and seven years ago.";
// output:
// False
Console.WriteLine(simple_trie.AllSubstringValues(s).Any(e => e));
}
}
class TrieNode<TValue>
{
private TrieNode<TValue>[] nodes = null;
private TValue m_value = default(TValue);
private Char m_base;
public Char Base { get { return m_base; } }
public bool IsEnd { get { return !m_value.Equals(default(TValue)); } }
public TValue Value
{
get { return m_value; }
set { m_value = value; }
}
public IEnumerable<TrieNode<TValue>> Nodes { get { return nodes; } }
public TrieNode<TValue> this[char c]
{
get
{
if (nodes != null && m_base <= c && c < m_base + nodes.Length)
return nodes[c - m_base];
return null;
}
}
public TrieNode<TValue> AddChild(char c)
{
if (nodes == null)
{
m_base = c;
nodes = new TrieNode<TValue>[1];
}
else if (c >= m_base + nodes.Length)
{
Array.Resize(ref nodes, c - m_base + 1);
}
else if (c < m_base)
{
Char c_new = (Char)(m_base - c);
TrieNode<TValue>[] tmp = new TrieNode<TValue>[nodes.Length + c_new];
nodes.CopyTo(tmp, c_new);
m_base = c;
nodes = tmp;
}
TrieNode<TValue> node = nodes[c - m_base];
if (node == null)
{
node = new TrieNode<TValue>();
nodes[c - m_base] = node;
}
return node;
}
};
class Trie<TValue> : System.Collections.IEnumerable
{
private TrieNode<TValue> _root = new TrieNode<TValue>();
// This dummy enables C# 3.0 initialization syntax
public System.Collections.IEnumerator GetEnumerator()
{
return null;
}
public void Add(String s, TValue v)
{
TrieNode<TValue> node = _root;
foreach (Char c in s)
node = node.AddChild(c);
node.Value = v;
}
public bool Contains(String s)
{
TrieNode<TValue> node = _root;
foreach (Char c in s)
{
node = node[c];
if (node == null)
return false;
}
return node.IsEnd;
}
public TValue Find(String s_in)
{
TrieNode<TValue> node = _root;
foreach (Char c in s_in)
{
node = node[c];
if (node == null)
return default(TValue);
}
return node.Value;
}
public IEnumerable<TValue> FindAll(String s_in)
{
TrieNode<TValue> node = _root;
foreach (Char c in s_in)
{
node = node[c];
if (node == null)
break;
if (node.Value != null)
yield return node.Value;
}
}
public IEnumerable<TValue> AllSubstringValues(String s)
{
int i_cur = 0;
while (i_cur < s.Length)
{
TrieNode<TValue> node = _root;
int i = i_cur;
while (i < s.Length)
{
node = node[s[i]];
if (node == null)
break;
if (node.Value != null)
yield return node.Value;
i++;
}
i_cur++;
}
}
};
Here's the right syntax:
if(names.Contains(myName))
{
//success code//
}
if (names.Contains(myName))
{
//success code//
}