public void parse() throws IOException {
sta.nextTokenType();
cond();
if (sta.lastToken() != TOKEN_EOF)
throw new InvalidExpressionError(
"Expected end of expression. Got '" + sta.lastToken() + "' instead.");
}
private void expr() throws IOException {
switch (sta.lastToken()) {
case TOKEN_SUB:
// 0 - term
builder.buildOperand(0);
builder.buildOperator(OP_SUB);
sta.nextTokenType();
term();
builder.endOperator();
expr1();
break;
case TOKEN_ADD:
sta.nextTokenType();
term();
expr1();
break;
case TOKEN_ID:
case TOKEN_NUM:
case TOKEN_OSB:
term();
expr1();
break;
default:
throw new InvalidExpressionError(
"Expected [, a number with sign or an identifier. Got '"
+ sta.lastToken()
+ "' instead.");
}
}
private void expr1() throws IOException {
if (sta.lastToken() == TOKEN_ADD) builder.buildOperator(OP_ADD);
else if (sta.lastToken() == TOKEN_SUB) builder.buildOperator(OP_SUB);
else return;
sta.nextTokenType();
term();
builder.endOperator();
expr1();
}
private void term1() throws IOException {
if (sta.lastToken() == TOKEN_MUL) builder.buildOperator(OP_MUL);
else if (sta.lastToken() == TOKEN_DIV) builder.buildOperator(OP_DIV);
else if (sta.lastToken() == TOKEN_MOD) builder.buildOperator(OP_MOD);
else return;
sta.nextTokenType();
termp();
builder.endOperator();
term1();
}
private void termp() throws IOException {
switch (sta.lastToken()) {
case TOKEN_ID:
case TOKEN_NUM:
case TOKEN_OSB:
fact();
termp1();
break;
default:
throw new InvalidExpressionError(
"Expected [, a number or an identifier. Got '" + sta.lastToken() + "' instead.");
}
}
private void cond1() throws IOException {
if (sta.lastToken() == TOKEN_OR) {
builder.buildOperator(OP_OR);
sta.nextTokenType();
termb();
builder.endOperator();
cond1();
}
}
private void termp1() throws IOException {
if (sta.lastToken() == TOKEN_POW) {
sta.nextTokenType();
builder.buildOperator(OP_POW);
fact();
builder.endOperator();
termp1();
}
}
private void termb1() throws IOException {
if (sta.lastToken() == TOKEN_AND) {
builder.buildOperator(OP_AND);
sta.nextTokenType();
factb();
builder.endOperator();
termb1();
}
}
private void termb() throws IOException {
switch (sta.lastToken()) {
case TOKEN_NOT:
case TOKEN_OPAR:
case TOKEN_ADD:
case TOKEN_SUB:
case TOKEN_ID:
case TOKEN_NUM:
case TOKEN_OSB:
factb();
termb1();
break;
default:
throw new InvalidExpressionError(
"Expected not (!), (, [ +, -, a number or an identifier. Got '"
+ sta.lastToken()
+ "' instead.");
}
}
private void factb() throws IOException {
switch (sta.lastToken()) {
case TOKEN_NOT:
sta.nextTokenType();
factb();
builder.buildOperator(OP_NOT);
break;
case TOKEN_OPAR:
sta.nextTokenType();
cond();
if (sta.lastToken() != TOKEN_CPAR)
throw new InvalidExpressionError("Expected ). Got '" + sta.lastToken() + "' instead.");
sta.nextTokenType();
break;
case TOKEN_ADD:
case TOKEN_SUB:
case TOKEN_ID:
case TOKEN_NUM:
case TOKEN_OSB:
expr();
switch (sta.lastToken()) {
case TOKEN_EQ:
builder.buildOperator(OP_EQ);
break;
case TOKEN_NE:
builder.buildOperator(OP_NE);
break;
case TOKEN_GT:
builder.buildOperator(OP_GT);
break;
case TOKEN_GE:
builder.buildOperator(OP_GE);
break;
case TOKEN_LT:
builder.buildOperator(OP_LT);
break;
case TOKEN_LE:
builder.buildOperator(OP_LE);
break;
default:
throw new InvalidExpressionError(
"Expected relational operator (==, !=, >, >=, <, <=). Got '"
+ sta.lastToken()
+ "' instead.");
}
sta.nextTokenType();
expr();
builder.endOperator();
break;
default:
throw new InvalidExpressionError(
"Expected not (!), (, [, +, -, a number or an identifier. Got '"
+ sta.lastToken()
+ "' instead.");
}
}
private void fact() throws IOException {
if (sta.lastToken() == TOKEN_ID) {
builder.buildOperand(sta.getString());
sta.nextTokenType();
} else if (sta.lastToken() == TOKEN_NUM) {
builder.buildOperand(sta.getInt());
sta.nextTokenType();
} else if (sta.lastToken() == TOKEN_OSB) {
sta.nextTokenType();
expr();
if (sta.lastToken() != TOKEN_CSB)
throw new InvalidExpressionError("Expected ]. Got '" + sta.lastToken() + "' instead.");
sta.nextTokenType();
} else
throw new InvalidExpressionError(
"Expected [, a number or an identifier. Got '" + sta.lastToken() + "' instead.");
}