/* * * cdcl.class - an Java (JDK 1.1) applet to de-mystify C declaration * * RCS: * $Revision$ * $Date$ * * Description: * * this is a java applet to unscramble C declarations. * The code to parse C declaration is translated from the C code * described in K&R, 2nd edition, page 123. * * Parameters * name value description * * none * * Limitations and Comments: * * This applet can not handle declarations with function argument * types or qualifiers like const,volatile etc. * * * Development History: * who when why * MA_Muquit@fccc.edu Aug-03-1996 first cut */ import java.applet.*; import java.awt.*; import java.io.*; import java.net.*; import java.util.*; public class cdcl extends Applet { // consts final static char NAME ='1'; final static char PARENS ='2'; final static char BRACKETS ='3'; final static char EOF ='\033'; final static boolean gdebug=false; char tokentype=NAME; // last token type String token, // last token string name, // identifier name datatype, // data type=char,int, etc. out; // output string int gi=-1; // index for getchar() String istr; // c declation int length; // length of the input string // GUI stuff TextField textf; TextArea texta; public boolean error_found=false; public void init() { Font font; font=new Font("Courier",Font.PLAIN,12); GridBagLayout gridbag=new GridBagLayout(); this.setLayout(gridbag); // create the label Label lab=new Label("Declaration:"); constrain(this,lab, 0,0,1,1, GridBagConstraints.BOTH, GridBagConstraints.CENTER, 0.0, 0.0, 0, 0, 0, 0); // create the text field textf=new TextField(50); constrain(this,textf, 1,0,4,1, GridBagConstraints.BOTH, GridBagConstraints.CENTER, 0.0, 0.0, 0, 0, 0, 0); textf.setFont(font); // create text area texta=new TextArea(""); constrain(this,texta, 0,1,5,1, GridBagConstraints.BOTH, GridBagConstraints.CENTER, 1.0, 1.0, 2, 2, 2, 2); texta.setFont(font); texta.setForeground(Color.blue); texta.setEditable(false); } // respond to user actions public boolean action(Event evt,Object arg) { if (evt.target == textf) { String text=textf.getText(); if (text.length() > 0) { Unscramble(text); return (true); } } return (true); } void Unscramble(String str) { String result; /* ** initialize */ gi=-1; token=""; out=""; name=""; datatype=""; result=""; istr="" + str; length=istr.length(); Debug("string=" + istr); Debug ("length=" + length); gettoken(); datatype += token; dcl(); if (error_found == false) { result="" + name + " is" + out + datatype; SetText(result); } } // getchar() method // it just walks through a string return the character until EOF is // reached, EOF is denoted by 033 // depends on global var: istr,gi and length public char getchar() { if (gi >= (length-1)) return (EOF); return (istr.charAt(++gi)); } public void ungetchar() { if (gi >= 0) gi--; } // method returns the next token public char gettoken() { char c; token=""; while ((c=getchar()) == ' ' || c == '\t') ; if (c == '(') { SetErrorFlag(false); if ((c=getchar()) == ')') { token="()"; tokentype=PARENS; } else { ungetchar(); tokentype='('; } } else if (c == '[') { SetErrorFlag(false); while ((c=getchar()) != ']') { if (c == EOF) { SetErrorFlag(true); SetText("Error: no maching ] found"); return(c); } token += c; } if (c == EOF) tokentype=EOF; else tokentype=BRACKETS; } else if (isalpha(c) == true) { SetErrorFlag(false); token= "" + c; while (isalnum((c=getchar())) == true) { if (c == EOF) { SetErrorFlag(true); SetText("Error: No alpha numeric characters found"); break; } token += c; } ungetchar(); tokentype=NAME; } else { tokentype=c; } return (tokentype); } // public void SetErrorFlag(boolean flg) { if (flg == true) { error_found=true; texta.setForeground(Color.red); } else { error_found=false; texta.setForeground(Color.blue); } } // set text to text area public void SetText(String str) { texta.setText(str); } // parse a declarator public void dcl() { int ns; for (ns=0; gettoken() == '*'; ) ns++; dirdcl(); while (ns-- > 0) out += " pointer to "; } // parse a direct declarator public void dirdcl() { char type; SetErrorFlag(false); if (tokentype == '(') { dcl(); if (tokentype != ')') { SetErrorFlag(true); SetText("Error: Missing )"); return; } } else if (tokentype == NAME) { name = "" + token; } else { SetErrorFlag(true); SetText("Error: expected name or (dcl)"); return; } while ((type=gettoken()) == PARENS || type == BRACKETS) { if (type == EOF) { SetErrorFlag(true); SetText("Error: failed to parse"); return; } if (type == PARENS) { out += " function returning "; } else { if (token.length() > 1) { out += "" + " array[0.."; int a=Integer.parseInt(token)-1; out += a + "]"; out += " of "; } else { out += " array of "; } } } } // check if the character is an alphabet public boolean isalpha(char c) { if (((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z'))) { return (true); } return (false); } // check is the character is alpha numeric // [a-zA-Z0-9] public boolean isalnum(char c) { if (((c >= '0') && (c <= 9)) || ((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z'))) { return (true); } return (false); } // print Debug info public void Debug(String str) { if (gdebug == true) { System.out.println(str); } } /* ** taken from O'Reilly's Java in a Nutshell book ** makes laying out components easier. Java's GUI is horrible IMHO ** I code mainly in X/Motif. I also coded in M$ platform, but never ** saw anything as ugly as java's GUI methods. Sun better do something ** about it. */ public void constrain(Container container, Component component, int grid_x, int grid_y, int grid_width, int grid_height, int fill, int anchor, double weight_x, double weight_y, int top, int left, int bottom, int right) { GridBagConstraints c = new GridBagConstraints(); c.gridx = grid_x; c.gridy = grid_y; c.gridwidth = grid_width; c.gridheight = grid_height; c.fill = fill; c.anchor = anchor; c.weightx = weight_x; c.weighty = weight_y; if (top+bottom+left+right > 0) c.insets = new Insets(top, left, bottom, right); ((GridBagLayout)container.getLayout()).setConstraints(component, c); container.add(component); } }