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    • com.github.dakusui.lisj.Basic Maven / Gradle / Ivy

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    package com.github.dakusui.lisj;

import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;

import org.apache.commons.lang3.ArrayUtils;

import com.github.dakusui.jcunit.core.Utils;
import com.github.dakusui.jcunit.exceptions.JCUnitException;
import com.github.dakusui.jcunit.exceptions.ObjectUnderFrameworkException;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;

public class Basic {
	public static final Object NIL = new Object[0];
	
	public static boolean eq(Object a, Object b) {
		if (a == b) return true;
		if (a == null || b == null) return false;
		if (a.equals(b)) return true;
		if (a instanceof Object[] && b instanceof Object[]) return Arrays.deepEquals( ((Object[])a), ((Object[]) b) );
		if (a instanceof Number && b instanceof Number) return Utils.bigDecimal((Number)a).equals(Utils.bigDecimal((Number)b));
		return a.equals(b);
	}
	
	public static Object cons(Object car, Object cdr) {
		if (eq(cdr, NIL)) return new Object[]{car};
		return new Object[]{car, cdr};
	}
	
	public static Object car(Object var) {
		if (var == null) throw new NullPointerException();
		if (atom(var)) throw new IllegalArgumentException();
		Object[] vars = (Object[])var;
		if (vars.length == 0) return NIL;
		if (normalizeNIL(vars[0]) == NIL) return NIL;
		return vars[0];
	}
	
	public static Object cdr(Object var) {
		if (var == null) throw new NullPointerException();
		if (eq(NIL, var)) return NIL;
		if (atom(var)) throw new IllegalArgumentException();
		Object[] vars = (Object[])var;
		if (vars.length == 1) return NIL;
		if (vars.length == 2) { 
			if (atom(vars[1])) {
				if (eq(vars[1], NIL)) return new Object[]{NIL};
				return new Object[]{vars[1]};
			} else 	return vars[1];
		} 
		return ArrayUtils.subarray(vars, 1, vars.length);
	}
	
	/**
	 * Returns the length of a given obj as an S-expression.
	 * If obj is an atom and not NIL, IllegalArgumentException 
	 * will be thrown.
	 */
	public static int length(Object obj) {
		if (obj == null) throw new NullPointerException();
		if (!(obj instanceof Object[])) throw new IllegalArgumentException();
		Object[] arr = ((Object[])obj);
		int len;
		if ((len = arr.length) <= 1) return len;
		return length(arr[len - 1], len);
	}
	
	private static int length(Object obj, int len) {
		if (atom(obj)) return len;
		Object[] arr = (Object[]) obj;
		if (arr.length <= 1) return len;
		return length(arr[arr.length - 1], len + arr.length - 1);
	}
	
	public static Object eval(Context context, Object var) throws JCUnitException, CUT {
		if (atom(var)) {
			if (var instanceof Symbol) {
				return context.lookup((Symbol)var);
			} else {
				return Utils.normalize(var);
			}
		}
		Object car = car(var);
		Object cdr = cdr(var);
		Form f = null;
		if (car instanceof Form) {
			f = (Form) car;
		} else if (car instanceof Symbol) {
			Object o = context.lookup((Symbol)car);
			if (!(o instanceof Form)) 
				throw new RuntimeException();
			f = (Form) o;
		} else {
			String msg = String.format("car(%s) of var(%s) must be a form or a symbol.", tostr(car), tostr(var));
			throw new IllegalArgumentException(msg);
		}
		if (eq(NIL, cdr)) {
			return f.evaluate(context, NIL);
		} 
		return f.evaluate(context, cdr);
	}
	
	private static Object normalizeNIL(Object var) {
		if (var instanceof Object[] && ((Object[])var).length == 0) return NIL;
		return var;
	}
	
	public static Object quote(Object o) {
		return o;
	}

	public static Object[] quote(Object... o) {
		return o;
	}
	
	public static Object[] toarr(Object o) {
		if (eq(o, NIL)) return (Object[])NIL;
		if (atom(o)) return new Object[]{o};
		Object[] arr = (Object[])o;
		Object last = arr[arr.length - 1];
		if (atom(last)) return arr;
		Object[] ret = new Object[length(arr)];
		for (int cur = 0; ; arr = (Object[]) last, last = arr[arr.length - 1]) {
			System.arraycopy(arr, 0, ret, cur, arr.length - 1);
			cur += arr.length - 1;
			if (atom(last)) break;
		}
		ret[ret.length - 1] = arr[arr.length - 1];
		return ret;
	}

	public static boolean atom(Object var) {
		if (var == null) return true;
		if (var instanceof Object[]) {
			return ((Object[])var).length == 0;
		} 
		return true;
	}
	
	public static Object arr(Object funcName, Object... args) {
		return new Object[]{new Symbol(funcName.toString()), args};
	}

	public static boolean evalp(Context context, Object predicate) throws JCUnitException, CUT {
		Object value = eval(context, predicate);
		if (value instanceof Boolean) {
			return ((Boolean)value);
		}
		String message = String.format("'%s' returned non-boolean value or it is not a predicate", predicate);
		throw new ObjectUnderFrameworkException(message, null);
	}
	
	public static abstract class SexpIterator implements Iterator, Iterable {
	}
	public static class ConsIterator extends SexpIterator {
			private ConsIterator(Object target) {
			if (atom(target)) throw new IllegalArgumentException();
			this.target = target;
		}

		@Override
		public Iterator iterator() {
			return this;
		}

		int cur = 0;
		Object target;
		
		@Override
		public boolean hasNext() {
			if (cur < ((Object[])target).length) return true;
			return false;
		}

		@Override
		public Object next() {
			int len = ((Object[])target).length;
			if (cur >= len) throw new NoSuchElementException();
			if (cur == len - 1)	 {
				Object last;
				if (atom(last = ((Object[])target)[cur])) {
					cur ++;
					return last;
				} else {
					cur = 1;
					target = last;
					return ((Object[])last)[0];	
				}
			}
			return ((Object[])target)[cur++];
		}

		@Override
		public void remove() {
			throw new UnsupportedOperationException();
		}
	}
	/*
	 * obj_ must be a cons.
	 */
	public static SexpIterator iterator(final Object obj) {
		if (atom(obj) || length(obj) == 1) return new SexpIterator() {
			boolean hasNext = true;
			@Override
			public boolean hasNext() {
				return this.hasNext;
			}
			@Override
			public Object next() {
				this.hasNext = false;
				return obj;
			}
			@Override
			public void remove() {
				throw new UnsupportedOperationException();
			}
			@Override
			public Iterator iterator() {
				return this;
			}
		};
		return new ConsIterator(obj);
	}
	
	/*
	 * obj must be a cons.
	 */
	public static Object get(Object obj, int index) {
		if (atom(obj)) throw new IllegalArgumentException();
		int len = ((Object[])obj).length;
		if (index < len - 1) return ((Object[])obj)[index];
		else if (index == len - 1) {
			if (atom(((Object[])obj)[index]) || len == 1) {
				return ((Object[])obj)[index];				
			}
		}
		Object last;
		if (atom(last = ((Object[])obj)[len - 1])) {
			throw new ArrayIndexOutOfBoundsException();
		}
		return get(last, index - (len - 1));
	}
	
	public static String tostr(Object obj) {
		return tostr(obj, false);
	}
	
	public static String tostr(Object obj, boolean suppressObjectId) {
		if (obj == null) return "null";
		if (eq(obj, NIL)) return "NIL";
		if (atom(obj)) return toString(obj, suppressObjectId);

		StringBuilder builder = new StringBuilder(1024);
		Object[] cons = (Object[]) obj;
		tostr(cons, builder, true, suppressObjectId);
		return builder.toString();
	}

	/*
	 * If 'obj''s toString is not overridden, this method returns a bit more
	 * concise string than the one java.lang.Object#toString method returns,
	 * i.e. package names will be omitted.
	 * And 'obj' is null, null itself will be returned.
	 * Otherwise, the result of 'obj.toString()' will be returned.
	 */
	private static String toString(Object obj, boolean suppressObjectId) {
		if (obj == null) return null;
		if (obj instanceof Class)
			return ((Class)obj).getSimpleName() + ".class";
		try {
			if (obj instanceof String) {
				String str = (String) obj;
				////
				// if str looks an FQCN, make it compact.
				return makeFqcnLikeStringCompact(str);
			} else {
				Method objToString = obj.getClass().getMethod("toString");
				////
				// Checking if 'toString' method is overridden or not.
				Class declaringClass = objToString.getDeclaringClass();
	 			if (declaringClass == Object.class) {
	 				String simpleName = obj.getClass().getSimpleName();
	 				if (suppressObjectId) {
	 					return simpleName + ".obj";
	 				}
					return simpleName + "@" + objectId(obj);
				}
			}
		} catch (SecurityException e) {
		} catch (NoSuchMethodException e) {
		}
		return obj.toString();
	}

	/**
	 * If a given string looks like an FQCN, this method creates and returns a 
	 * compact version of it. Otherwise it return the original string itself.
	 * 
	 * @param str A string
	 * @return A compact version of str or str itself.
	 */
	private static String makeFqcnLikeStringCompact(String str) {
		int i;
		////
		// If it doesn't start or end with a dot and two or more dots are found in the
		// string, this method considers that it looks like an FQCN.
		if (str.endsWith(".")) return str;
		////
		// Also if it contains a white space, this method doesn't consider it is
		// an FQCN.
		if (str.contains(" ")) return str;
		if ((i = str.indexOf('.')) > 0) {
			if ((str.indexOf('.', i + 1)) > i) {
				return str.substring(str.lastIndexOf('.') + 1);
			}
		}
		return str;
	}
	
	private static int nextObjectId = 1;
	
	private static final Map objectMap = CacheBuilder.newBuilder().weakKeys().build(new CacheLoader(){
		@Override
		public Integer load(Object key) throws Exception {
			return nextObjectId++;
		}}).asMap();
	
	private static int objectId(Object obj) {
		if (obj == null) return 0;
		if (!objectMap.containsKey(obj)) {
			objectMap.put(obj, nextObjectId++);
		}
		return objectMap.get(obj);
	}
	
	private static void tostr(Object[] cons, StringBuilder builder, boolean withParentheses, boolean suppressObjectId) {
		if (withParentheses) builder.append("(");
		try {
			for (int i = 0; i < cons.length; i++) {
				Object cur = cons[i];
				if (cons.length == 1 || i != cons.length - 1) {
					if (!atom(cur)) {
						tostr((Object[])cur, builder, true, suppressObjectId);
					} else {
						builder.append(tostr(cur, suppressObjectId)); 
					}
					if (i != cons.length -1) builder.append(",");
				} else if (atom(cur)) { 
					if (eq(cur, NIL)) builder.append("NIL");
					else builder.append(tostr(cur, suppressObjectId));
				} else {
					// cur is a cons at the end of the cons.
					tostr((Object[]) cur, builder, false, suppressObjectId);
				}
			}
		} finally {
			if (withParentheses) builder.append(")");
		}
	}
}
    
    
    
    

    




    
    
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