An algorithm for auto-indexing parentheses in code

Question

im is working on a code editor (WinForms), and I want to know how to execute the {and} function, in particular, auto-tasks using brackets (open and close), as in a real code editor.

--- | > {and}

like this 1:

The editor was richtextbox named rtb.

Answer 1

Before reading and using codes, read the following texts:

• I don’t have enough time to write better codes. I was just trying to write a sample for you.
• I just wrote the codes in a simple way, not in OOP .
• You can improve codes with Enums , Properties , Classes, and other OOP stuff .
• You can improve the logic of codes ; and you can use multi-threading to achieve better performance .
• This example is not exhaustive . I only applied the Auto-Indention example for a semicolon (;) . "

I have to say some tips on using codes:

• rtbCodes is the name of the RichTextBox control in the form in the sample project.
• frmCodeEditor is the name of the form in the sample project.

You can download the sample project at the following addresses:

4Shared -> Auto-Indention for Code Editor

SendSpace -> Auto-Indention for Code Editor

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Diagnostics; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication2 { public partial class frmCodeEditor : Form { char[] chrTracingKeyChars = new char[] { ';', '}', '\n' }; char[] chrCheckingKeyChars = new char[] { '{', '(' }; Point ptCurrentCharPosition; bool bolCheckCalling = false; int intInitialCursorPosition = 0; int intRemainingCharsOfInitialText = 0; int intNextCharIndex = 0; int intPrevCharIndex = 0; public frmCodeEditor() { InitializeComponent(); } private void richTextBox1_TextChanged(object sender, EventArgs e) { AutoIndention(rtbCodes); } /// <summary> /// Implements Auto-Indention. /// </summary> /// <param name="rtb">A RichTextBox control</param> private void AutoIndention(RichTextBox rtb) { char chrLastChar = GetChar(rtb); if (chrLastChar == chrTracingKeyChars[0]) { intRemainingCharsOfInitialText = rtb.TextLength - rtb.SelectionStart; intInitialCursorPosition = rtb.SelectionStart; ImplementIndentionForSemicolon(rtb); } else if (chrLastChar == chrTracingKeyChars[1]) { ImplementIndentionForRightCurlyBracket(rtb); } else if (chrLastChar == chrTracingKeyChars[2]) { ImplementIndentionForNewLineCharacter(rtb); } } /// <summary> /// Specifies current char based on the cursor position. /// </summary> /// <param name="rtb">A RichTextBox control</param> /// <returns>Returns a char.</returns> private char GetChar(RichTextBox rtb) { return GetChar(rtb.SelectionStart, rtb); } /// <summary> /// Specifies a char based on the specified index. /// </summary> /// <param name="intCharIndex">A char index</param> /// <param name="rtb">A RichTextBox control</param> /// <returns>Returns a char.</returns> private char GetChar(int intCharIndex, RichTextBox rtb) { if (intCharIndex != rtb.TextLength) { ptCurrentCharPosition = rtb.GetPositionFromCharIndex(intCharIndex - 1); } else { ptCurrentCharPosition = rtb.GetPositionFromCharIndex(intCharIndex); } return rtb.GetCharFromPosition(ptCurrentCharPosition); } /// <summary> /// Specifies current line number based on the cursor position. /// </summary> /// <param name="rtb">A RichTextBox control</param> /// <returns>Returns the line number.</returns> private int GetLineNumber(RichTextBox rtb) { return GetLineNumber(rtb.GetFirstCharIndexOfCurrentLine(), rtb); } /// <summary> /// Specifies the line number based on the specified index. /// </summary> /// <param name="intCharIndex">A char index</param> /// <param name="rtb">A RichTextBox control</param> /// <returns>Returns the line number.</returns> private int GetLineNumber(int intCharIndex, RichTextBox rtb) { return rtb.GetLineFromCharIndex(intCharIndex); } /// <summary> /// Implements indention for semicolon ";" character. /// </summary> /// <param name="rtb">A RichTextBox control</param> private void ImplementIndentionForSemicolon(RichTextBox rtb) { Dictionary<char, int> dicResult = IsExistCheckingKeyChars(rtb); if (dicResult[chrCheckingKeyChars[0]] != -1) { int intIndentionLevel = CheckingIndentionLevel(dicResult[chrCheckingKeyChars[0]], rtb); ImplementIndention(dicResult[chrCheckingKeyChars[0]], intIndentionLevel, rtb); } } private void ImplementIndentionForRightCurlyBracket(RichTextBox rtb) { } private void ImplementIndentionForNewLineCharacter(RichTextBox rtb) { } /// <summary> /// Checks current and previous lines for finding key-chars. /// </summary> /// <param name="rtb">A RichTextBox control</param> /// <param name="bolSearchCurrentLine">The search state</param> /// <returns>Returns first occurrences of key-chars before current char.</returns> private Dictionary<char, int> IsExistCheckingKeyChars(RichTextBox rtb, bool bolSearchCurrentLine = false) { GetChar(rtb); Dictionary<char, int> dicCheckingKeyCharsIndexes = new Dictionary<char, int>(); for (int intCntr = 0; intCntr < chrCheckingKeyChars.Length; intCntr++) { dicCheckingKeyCharsIndexes.Add(chrCheckingKeyChars[intCntr], 0); } for (int intCntr = 0; intCntr < chrCheckingKeyChars.Length; intCntr++) { int intFirstIndexForChecking = 0; int intLastIndexForChecking = 0; for (int intLineCounter = GetLineNumber(rtb); intLineCounter >= 0; intLineCounter--) { if (intLineCounter == GetLineNumber(rtb)) { intLastIndexForChecking = rtb.GetCharIndexFromPosition(ptCurrentCharPosition); } else { intLastIndexForChecking = intFirstIndexForChecking - 1; } intFirstIndexForChecking = rtb.GetFirstCharIndexFromLine(intLineCounter); try { dicCheckingKeyCharsIndexes[chrCheckingKeyChars[intCntr]] = rtb.Find(chrCheckingKeyChars[intCntr].ToString(), intFirstIndexForChecking, rtb.GetCharIndexFromPosition(ptCurrentCharPosition), RichTextBoxFinds.NoHighlight | RichTextBoxFinds.None); if (dicCheckingKeyCharsIndexes[chrCheckingKeyChars[intCntr]] != -1) { do { if (rtb.Find(chrCheckingKeyChars[intCntr].ToString(), intFirstIndexForChecking, rtb.GetCharIndexFromPosition(ptCurrentCharPosition), RichTextBoxFinds.NoHighlight | RichTextBoxFinds.None) != -1) { dicCheckingKeyCharsIndexes[chrCheckingKeyChars[intCntr]] = rtb.Find(chrCheckingKeyChars[intCntr].ToString(), intFirstIndexForChecking, rtb.GetCharIndexFromPosition(ptCurrentCharPosition), RichTextBoxFinds.NoHighlight | RichTextBoxFinds.None); } intFirstIndexForChecking++; } while (intFirstIndexForChecking != rtb.GetCharIndexFromPosition(ptCurrentCharPosition)); break; } } catch { dicCheckingKeyCharsIndexes[chrCheckingKeyChars[intCntr]] = -1; break; } if (bolSearchCurrentLine) { break; } } } return dicCheckingKeyCharsIndexes; } /// <summary> /// Checks a line for calculating its indention level. /// </summary> /// <param name="intCharIndex">A char index</param> /// <param name="rtb">A RichTextBox control</param> /// <returns>Returns indention level of the line.</returns> private int CheckingIndentionLevel(int intCharIndex, RichTextBox rtb) { int intLineNumber = GetLineNumber(intCharIndex, rtb); int intIndentionLevelNumber = 0; intCharIndex = rtb.GetFirstCharIndexFromLine(intLineNumber); char chrChar = GetChar(intCharIndex, rtb); if (chrChar == '\n') { chrChar = GetChar(++intCharIndex, rtb); } if (chrChar != ' ') { return 0; } else { int intSpaceCntr = 0; while(chrChar == ' ') { chrChar = GetChar(++intCharIndex, rtb); if (chrChar == ' ') { intSpaceCntr++; } if (intSpaceCntr % 4 == 0 && intSpaceCntr != 0) { intIndentionLevelNumber++; intSpaceCntr = 0; } } if (intSpaceCntr % 4 != 0) { intIndentionLevelNumber++; } } return intIndentionLevelNumber; } /// <summary> /// Implements Indention to the codes /// </summary> /// <param name="intCharIndex">A char index</param> /// <param name="intIndentionLevel">The number of indention level</param> /// <param name="rtb">A RichTextBox control</param> private void ImplementIndention(int intCharIndex, int intIndentionLevel, RichTextBox rtb) { intNextCharIndex = intCharIndex; intPrevCharIndex = intCharIndex; int intKeyCharsNumberInLine = 1; int intCurrentLineNumber = GetLineNumber(rtb); int intKeyCharLineNumber = GetLineNumber(intNextCharIndex, rtb); string[] strLinesTexts; Dictionary<char, int> dicResult; do { rtb.SelectionStart = intPrevCharIndex; dicResult = IsExistCheckingKeyChars(rtb); if (dicResult[chrCheckingKeyChars[0]] != -1) { intKeyCharsNumberInLine++; intPrevCharIndex = dicResult[chrCheckingKeyChars[0]]; } } while (dicResult[chrCheckingKeyChars[0]] != -1); if (!bolCheckCalling) { if (intCurrentLineNumber == intKeyCharLineNumber) { for (int intCntr = 1; intCntr <= intKeyCharsNumberInLine; intCntr++) { do { rtb.SelectionStart = intPrevCharIndex; dicResult = IsExistCheckingKeyChars(rtb, true); if (dicResult[chrCheckingKeyChars[0]] != -1) { intPrevCharIndex = dicResult[chrCheckingKeyChars[0]]; } } while (dicResult[chrCheckingKeyChars[0]] != -1); bolCheckCalling = true; ImplementIndention(intPrevCharIndex, rtb); } return; } } bolCheckCalling = false; rtb.SelectionStart = intNextCharIndex; rtb.SelectionLength = 1; rtb.SelectedText = "\n" + rtb.SelectedText; intCurrentLineNumber = GetLineNumber(rtb); strLinesTexts = rtb.Lines; strLinesTexts[intCurrentLineNumber] = strLinesTexts[intCurrentLineNumber].Trim(); for (int intIndentionCntr = 1; intIndentionCntr <= intIndentionLevel; intIndentionCntr++) { for (int intSpaceCntr = 1; intSpaceCntr <= 4; intSpaceCntr++) { strLinesTexts[intCurrentLineNumber] = ' ' + strLinesTexts[intCurrentLineNumber]; } } rtb.Lines = strLinesTexts; rtb.SelectionStart = intNextCharIndex + ((intIndentionLevel * 4) + 1); intNextCharIndex = rtb.SelectionStart; rtb.SelectionLength = 1; rtb.SelectedText = rtb.SelectedText + "\n"; intCurrentLineNumber = GetLineNumber(rtb); strLinesTexts = rtb.Lines; strLinesTexts[intCurrentLineNumber] = strLinesTexts[intCurrentLineNumber].Trim(); for (int intIndentionCntr = 1; intIndentionCntr <= intIndentionLevel + 1; intIndentionCntr++) { for (int intSpaceCntr = 1; intSpaceCntr <= 4; intSpaceCntr++) { strLinesTexts[intCurrentLineNumber] = ' ' + strLinesTexts[intCurrentLineNumber]; } } rtb.Lines = strLinesTexts; rtb.SelectionStart = intInitialCursorPosition + ((rtb.TextLength - intInitialCursorPosition) - intRemainingCharsOfInitialText); intNextCharIndex = rtb.SelectionStart; intPrevCharIndex = intNextCharIndex; } /// <summary> /// Implements Indention to the codes /// </summary> /// <param name="intCharIndex">A char index</param> /// <param name="rtb">A RichTextBox control</param> private void ImplementIndention(int intCharIndex, RichTextBox rtb) { int intIndentionLevel = CheckingIndentionLevel(intCharIndex, rtb); ImplementIndention(intCharIndex, intIndentionLevel, rtb); } } } 

I hope these code examples help you.

Please update and share codes if you improve them.

Answer 2

ok my buggy solution, but enough for you to understand how it works.

my result:

 { { { } } } 

and here is my code

 public partial class Form1 : Form { private bool FLAG_Selftimer = false; private bool FLAG_KeyPressed = false; private int pos = 0; public Form1() { InitializeComponent(); } private void richTextBox1_TextChanged(object sender, EventArgs e) { var rtb = sender as RichTextBox; var point = rtb.SelectionStart; if (!FLAG_Selftimer) { rtb.Text = ReGenerateRTBText(rtb.Text); FLAG_KeyPressed = false; } else { point ++; FLAG_Selftimer = false; } rtb.SelectionStart = point; } private string ReGenerateRTBText(string Text) { string[] text = Regex.Split(Text,"\n"); int lvl = 0; string newString = ""; foreach (string line in text) { line.TrimStart(' '); newString += indentation(lvl) + line.TrimStart(' ') + "\n"; if (line.Contains("{")) lvl++; if (line.Contains("}")) lvl--; } FLAG_Selftimer = true; return (!FLAG_KeyPressed) ? newString : newString.TrimEnd('\n'); } private string indentation(int IndentLevel) { string space = ""; if(IndentLevel>0) for (int lvl = 0; lvl < IndentLevel; lvl++) { space += " ".PadLeft(8); } return space; } private void richTextBox1_KeyPress(object sender, KeyPressEventArgs e) { FLAG_KeyPressed = true; } } 

Hope this helps you