342 FuncLang Console

Printer.java

/** Replace the first two print() methods with this **/

public void print(Value v) {
  if(v.tostring() != "")
    System.out.println("=> "+v.tostring());
}
public void print(Exception e) {
  System.out.println("Error: "+e.toString());
}

Reader.java

package funclang;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.FileReader;

import funclang.AST.Program;
import funclang.parser.FuncLangLexer;
import funclang.parser.FuncLangParser;

public class Reader {
	
	private final static String TAB = "    ";
	
	Program read() throws IOException {
		String programText = readNextProgram();
		return parse(programText);
	}

	Program parse(String programText) {
		FuncLangLexer l = new FuncLangLexer(new org.antlr.v4.runtime.ANTLRInputStream(programText));
		FuncLangParser p = new FuncLangParser(new org.antlr.v4.runtime.CommonTokenStream(l));
		Program program = p.program().ast;
		return program;
	}
	
	static String readFile(String fileName) throws IOException {
		try (BufferedReader br = new BufferedReader(
				new FileReader(fileName))) {
			StringBuilder sb = new StringBuilder();
			String line = br.readLine();

			while (line != null) {
				sb.append(line);
				sb.append(System.lineSeparator());
				line = br.readLine();
			}
			return sb.toString();
		}
	}
	
	private String readNextProgram() throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		System.out.print(" > ");
		String programText = br.readLine();
		
		boolean confirmed = false;
		String indents = "";
		
		while (!checkParens(programText) && !confirmed) {
			indents = genTabs(countOpenParens(programText));
			System.out.print(".. "+indents);
			String line = br.readLine();
			programText += line;
			
			if (line.trim().length() == 0){
				confirmed = true;
			}
		}
		
		return runFile(programText);
	}
	
	private String genTabs(int num) {
		StringBuilder sb = new StringBuilder();
		for (int i=0; i<num; i++)
			sb.append(TAB);
		return sb.toString();
	}
	
	private boolean checkParens(String program) {
		int count = 0;
		for (char c: program.toCharArray()) {
			if (c == '(')
				count++;
			if (c == ')')
				count--;
			if (count < 0)
				return false;
		}
		return (count == 0);
	}
	
	private int countOpenParens(String program) {
		int count = 0;
		for (char c: program.toCharArray()){
			if (c == '(')
				count++;
			if (c == ')')
				count--;
		}
		return count;
	}
	
	private String runFile(String programText) throws IOException {
		if(programText.startsWith("run ")){
			programText = readFile("build/funclang/examples/" + programText.substring(4));
		}
		return programText; 
	}
}