我正在ANTLR和Java上做一个伪编程语言。我遇到了一些无法处理的问题：
If、else if 和 else：每个条件仅执行一个语句，因此其他语句将被跳过。例如：
else { show(a); show(b); }anull我无法制作 arrayAccess，这意味着我无法制作此：
int b = array[1]show(array[2])考虑以下函数并调用：
public string fun(string a) {
return "Haiii, " + a + "!\n";
}
string greet = fun("John")
greet这是我的 GrammarsVisitor.java:
import java.util.HashMap;
import java.util.Map;
import java.util.Stack;
import java.util.List;
import java.util.ArrayList;
public class GrammarsVisitor extends GrammarBaseVisitor<Object> {
private final Stack<Map<String, Object>> scopes = new Stack<>();
private final Map<String, FunctionDefinition> functions = new HashMap<>();
public GrammarsVisitor() {
// Push the global scope
scopes.push(new HashMap<>());
}
@Override
public Object visitVariable(GrammarParser.VariableContext ctx) {
String type = ctx.TYPE().getText();
String variableName = ctx.ID().getText();
Object value = null;
// If the variable is initialized
if (ctx.expression() != null) {
value = visitExpression(ctx.expression());
}
// Storing the variable in the current scope based on its type
switch (type) {
case "int":
if (value == null) {
value = 0;
} else {
value = Integer.parseInt(value.toString());
}
break;
case "float":
if (value == null) {
value = 0.0f;
} else {
value = Float.parseFloat(value.toString());
}
break;
case "string":
if (value == null) {
value = "";
} else {
value = value.toString();
}
break;
case "bool":
if (value == null) {
value = false;
} else {
value = Boolean.parseBoolean(value.toString());
}
break;
default:
throw new RuntimeException("Unknown type: " + type);
}
// Adding the variable to the current scope
if (scopes.peek().containsKey(variableName)) {
throw new RuntimeException("Variable already declared in the current scope: " + variableName);
}
scopes.peek().put(variableName, value);
System.out.println("Variable declared: " + type + " " + variableName + " = " + value);
return null;
}
@Override
public Object visitArray(GrammarParser.ArrayContext ctx) {
String type = ctx.TYPE() != null ? ctx.TYPE().getText() : ctx.ID(0).getText();
String arrayName = ctx.ID(0).getText();
java.util.List<Object> array = new java.util.ArrayList<>();
// If the array is initialized
if (ctx.arrayInit() != null) {
for (GrammarParser.ExpressionContext exprCtx : ctx.arrayInit().expression()) {
array.add(visitExpression(exprCtx));
}
}
// Adding the array to the current scope
if (scopes.peek().containsKey(arrayName)) {
throw new RuntimeException("Array already declared in the current scope: " + arrayName);
}
scopes.peek().put(arrayName, array);
System.out.println("Array declared: " + type + "[] " + arrayName + " = " + array);
return null;
}
public Object visitExpression(GrammarParser.ExpressionContext ctx) {
if (ctx.functionCall() != null) {
return visitFunctionCall(ctx.functionCall());
}
if (ctx.BOOL() != null) {
return Boolean.parseBoolean(ctx.BOOL().getText());
} else if (ctx.INT() != null) {
return Integer.parseInt(ctx.INT().getText());
} else if (ctx.FLOAT() != null) {
return Float.parseFloat(ctx.FLOAT().getText());
} else if (ctx.STRING() != null) {
return ctx.STRING().getText()
.replace("\"", "")
.replace("\\n", "\n")
.replace("\\t", "\t");
} else if (ctx.ID() != null) {
String variableName = ctx.ID().getText();
for (int i = scopes.size() - 1; i >= 0; i--) {
if (scopes.get(i).containsKey(variableName)) {
return scopes.get(i).get(variableName);
}
}
throw new RuntimeException("Undefined variable: " + variableName);
} else if (ctx.getChildCount() == 3 && ctx.getChild(0).getText().equals("(") && ctx.getChild(2).getText().equals(")")) {
return visitExpression(ctx.expression(0));
} else if (ctx.getChildCount() == 2 && ctx.getChild(0).getText().equals("!")) {
return !(Boolean) visitExpression(ctx.expression(0));
} else if (ctx.getChildCount() == 3) {
Object left = visitExpression(ctx.expression(0));
Object right = visitExpression(ctx.expression(1));
String operator = ctx.getChild(1).getText();
switch (operator) {
case "%":
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left % (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) % Float.parseFloat(right.toString());
}
break;
case "+":
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left + (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) + Float.parseFloat(right.toString());
} else if (left instanceof String || right instanceof String) {
return left.toString() + right.toString();
}
break;
case "-":
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left - (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) - Float.parseFloat(right.toString());
}
break;
case "*":
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left * (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) * Float.parseFloat(right.toString());
}
break;
case "/":
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left / (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) / Float.parseFloat(right.toString());
}
break;
case "&&":
return (Boolean) left && (Boolean) right;
case "||":
return (Boolean) left || (Boolean) right;
case "==":
return left.equals(right);
case "!=" :
return !left.equals(right);
case "<":
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left < (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) < Float.parseFloat(right.toString());
}
break;
case ">":
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left > (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) > Float.parseFloat(right.toString());
}
break;
case "<=" :
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left <= (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) <= Float.parseFloat(right.toString());
}
break;
case ">=" :
if (left instanceof Integer && right instanceof Integer) {
return (Integer) left >= (Integer) right;
} else if (left instanceof Float || right instanceof Float) {
return Float.parseFloat(left.toString()) >= Float.parseFloat(right.toString());
}
break;
default:
throw new RuntimeException("Unsupported operator: " + operator);
}
}
throw new RuntimeException("Invalid expression: " + ctx.getText());
}
@Override
public Object visitFunction(GrammarParser.FunctionContext ctx) {
String functionName = ctx.ID(0).getText();
List<String> paramNames = new ArrayList<>();
if (ctx.TYPE() != null && ctx.ID().size() > 1) {
for (int i = 1; i < ctx.ID().size(); i++) {
paramNames.add(ctx.ID(i).getText());
}
}
functions.put(functionName, new FunctionDefinition(ctx, paramNames));
System.out.println("Function declared: " + functionName);
return null;
}
@Override
public Object visitFunctionCall(GrammarParser.FunctionCallContext ctx) {
String functionName = ctx.ID(0).getText();
FunctionDefinition functionDef = functions.get(functionName);
if (functionDef == null) {
throw new RuntimeException("Undefined function: " + functionName);
}
// Creating a new scope for function call
scopes.push(new HashMap<>());
// Assign parameter values to new scope
List<GrammarParser.ExpressionContext> args = ctx.expression();
for (int i = 0; i < args.size(); i++) {
String paramName = functionDef.paramNames.get(i);
Object paramValue = visitExpression(args.get(i));
scopes.peek().put(paramName, paramValue);
}
// Execute the function body
Object returnValue = null;
for (GrammarParser.StatementContext stmtCtx : functionDef.functionCtx.statement()) {
returnValue = visit(stmtCtx);
if (returnValue != null) {
break;
}
}
// Pop the function scope
scopes.pop();
return returnValue;
}
@Override
public Object visitReturnStatement(GrammarParser.ReturnStatementContext ctx) {
return visitExpression(ctx.expression());
}
@Override
public Object visitShow(GrammarParser.ShowContext ctx) {
Object value = visitExpression(ctx.expression());
System.out.println(value);
return null;
}
@Override
public Object visitLoop(GrammarParser.LoopContext ctx) {
String loopVariable = ctx.ID().getText();
Object start = visitExpression(ctx.expression(0));
Object end = visitExpression(ctx.expression(1));
if (!(start instanceof Integer) || !(end instanceof Integer)) {
throw new RuntimeException("The 'for' loop must have integer start and end values: " + ctx.getText());
}
int startValue = (Integer) start;
int endValue = (Integer) end;
if (startValue <= endValue) {
for (int i = startValue; i <= endValue; i++) {
scopes.peek().put(loopVariable, i);
for (GrammarParser.StatementContext stmtCtx : ctx.statement()) {
visit(stmtCtx);
}
}
} else {
for (int i = startValue; i >= endValue; i--) {
scopes.peek().put(loopVariable, i);
for (GrammarParser.StatementContext stmtCtx : ctx.statement()) {
visit(stmtCtx);
}
}
}
return null;
}
@Override
public Object visitIfStatement(GrammarParser.IfStatementContext ctx) {
for (int i = 0; i < ctx.expression().size(); i++) {
Object condition = visitExpression(ctx.expression(i));
if (!(condition instanceof Boolean)) {
throw new RuntimeException("The condition must be a boolean expression: " + ctx.expression(i).getText());
}
if ((Boolean) condition) {
visit(ctx.statement(i));
return null; // Exit after the first true condition block
}
}
// If none of the conditions are true and there's an 'else' block
if (ctx.statement().size() > ctx.expression().size()) {
visit(ctx.statement(ctx.expression().size()));
}
return null;
}
private static class FunctionDefinition {
GrammarParser.FunctionContext functionCtx;
List<String> paramNames;
FunctionDefinition(GrammarParser.FunctionContext functionCtx, List<String> paramNames) {
this.functionCtx = functionCtx;
this.paramNames = paramNames;
}
}
}
这是我的 Grammar.g4（感谢 Bart Kiers）：
grammar Grammar;
start : statement* EOF;
statement
: variable ';'
| objectInstance ';'
| array ';'
| ifStatement
| function
| loop
| functionCall ';'
| show ';'
| arrayAccess ';'
| class
| returnStatement ';'
;
function
: ACCESS TYPE ID '(' (TYPE ID (',' TYPE ID)*)? ')' '{' statement* '}'
| ACCESS 'void' ID '(' (TYPE ID (',' TYPE ID)*)? ')' '{' statement* '}'
;
variable : TYPE ID ('=' expression)?;
objectInstance : objectType=ID instanceName=ID ('=' expression)?;
array : (TYPE | ID) ID '[' ']' ('=' arrayInit)?;
ifStatement : 'if' '(' expression ')' '{' statement* '}' ('else if' '(' expression ')' '{' statement* '}')* ('else' '{' statement* '}')?;
loop : 'for' ID 'in' expression 'to' expression '{' statement* '}';
functionCall : (ID '.')? ID '(' (expression (',' expression)*?)? ')';
show : 'show' '(' expression ')';
class : 'class' ID '{' classEntries '}';
classEntries : ((variable ';') | (array ';') | function)*;
arrayInit : '[' expression (',' expression)* ']';
returnStatement: 'return' expression;
arrayAccess : ID '[' expression ']' ;
expression
: '(' expression ')'
| '!' expression
| expression ('&&' | '||') expression
| expression ('/' | '*' | '%') expression
| expression ('+' | '-') expression
| expression COMPARISON expression
| 'new' ID '(' ((expression | arrayInit) (',' (expression | arrayInit))*)? ')'
| functionCall
| STRING
| ID
| INT
| BOOL
| FLOAT
| ID
;
ACCESS : 'private' | 'public';
COMPARISON : '>' | '<' | '>=' | '<=' | '==';
TYPE : 'int' | 'float' | 'string' | 'bool';
BOOL : 'true' | 'false' ;
ID : [a-zA-Z_][a-zA-Z0-9_]* ;
STRING : '"' (~[\\"] | '\\' .)* '"';
INT : [0-9]+;
FLOAT : [0-9]+ '.' [0-9]+;
WS : [ \t\r\n]+ -> channel(HIDDEN);
LINE_COMMENT : '//' ~[\r\n]* -> skip;
BLOCK_COMMENT : '/*' .*? '*/' -> skip;
非常感谢您帮助了解问题所在。
您还应该重写访问者中的
Object visitStatement(GrammarParser.StatementContext ctx)尝试添加这个：
@Override
public Object visitStatement(GrammarParser.StatementContext ctx) {
if (ctx.variable() != null) return this.visitVariable(ctx.variable());
if (ctx.objectInstance() != null) return this.visitObjectInstance(ctx.objectInstance());
if (ctx.array() != null) return this.visitArray(ctx.array());
if (ctx.ifStatement() != null) return this.visitIfStatement(ctx.ifStatement());
if (ctx.function() != null) return this.visitFunction(ctx.function());
if (ctx.loop() != null) return this.visitLoop(ctx.loop());
if (ctx.functionCall() != null) return this.visitFunction(ctx.function());
if (ctx.show() != null) return this.visitShow(ctx.show());
if (ctx.arrayAccess() != null) return this.visitArrayAccess(ctx.arrayAccess());
if (ctx.class_() != null) return this.visitClass(ctx.class_());
if (ctx.returnStatement() != null) return this.visitReturnStatement(ctx.returnStatement());
throw new RuntimeException("Unexpected statement: " + ctx.getText());
}