Using https://github.com/JetBrains/Grammar-Kit https://github.com/JetBrains/Grammar-Kit如何在没有左递归的情况下重写语法?
grammar ::= exprs
exprs::= (sum_expr (';')?)*
private sum_expr::= sum_expr_infix | sum_expr_prefix
sum_expr_infix ::= number sum_expr_prefix
left sum_expr_prefix::= op_plus number
private op_plus ::= '+'
number ::= float | integer
float ::= digit+ '.' digit*
integer ::= digit+
private digit ::=('0'|'1'|'2'|'3'|'4'|'5'|'6'|'7'|'8'|'9')
输入示例:
10+20+30.0;
10+20+30.0
Answer shall maintain parse tree property that nodes contain 2/3 children:
![enter image description here](https://i.stack.imgur.com/meIBT.png)
这个问题引导了正确的方向:不使用左手递归解析布尔表达式 https://stackoverflow.com/questions/15506088/parsing-boolean-expression-without-left-hand-recursion
grammar ::= e*
e ::= math separator?
math ::= add
add ::=
mul op_plus math
| mul op_minus math
| mul
mul ::=
factorial op_mul mul
| factorial op_div mul
| factorial
factorial ::= term op_factorial space* | term
op_factorial ::= '!'
term ::= parentheses | space* number space*
parentheses ::= '(' math ')'
op_minus ::= '-'
op_plus ::= '+'
op_div ::= '/'
op_mul ::= '*'
number ::= float | integer
float ::= (digit+'.') digit*
integer ::=digit+
digit ::= '0'|'1'|'2'|'3'|'4'|'5'|'6'|'7'|'8'|'9'
space ::= ' ' | '\t'
separator ::= ';'
测试输入:
1!
3*2+1
3*2+1+3.0!
3*2+1 + 3.0!
1+1+(1+1)!
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