Parsing/Shunting-yard algorithm: Difference between revisions
add RPL
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(add RPL) |
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input: ) (
RPN──► ─────── error in expression ───────
</pre>
=={{header|RPL}}==
≪ "§" + → expression
≪ { }
1 expression SIZE '''FOR''' j
DUP TYPE NOT <span style="color:grey">@ 1 if a number is in top-stack position</span>
expression j DUP SUB
'''IF''' "0123456789" OVER POS '''THEN'''
STR→
'''IF''' SWAP '''THEN''' SWAP 10 * + '''END'''
'''ELSE'''
'''IF''' SWAP '''THEN''' ROT ROT + SWAP '''END'''
'''IF''' "^*/+-()" OVER POS '''THEN''' + '''ELSE''' DROP '''END'''
'''END'''
'''NEXT'''
≫ ≫ ‘<span style="color:blue">LEXER</span>’ STO <span style="color:grey">@ ( "1+(2*3)" → { 1 "+" "(" 2 "*" 3 ")" } )</span>
≪ '''IF''' ←depth '''THEN'''
"^*/+-" DUP 4 PICK POS SWAP 3 PICK POS
{ 4 3 3 2 2 } { 1 0 0 0 0 }
→ o1 o2 prec rasso
≪ '''IF''' o2 '''THEN'''
prec o1 GET prec o2 GET
'''IF''' rasso o1 GET '''THEN''' < '''ELSE''' ≤ '''END'''
'''ELSE''' 0 '''END'''
≫
'''ELSE''' DROP 0 '''END'''
≫ ‘<span style="color:blue">POPOP?</span>’ STO <span style="color:grey">@ ( op → Boolean )</span>
≪ <span style="color:blue">LEXER</span> { } "" 0 → infix postfix token ←depth
≪ 1 infix SIZE '''FOR''' j
infix j GET 'token' STO
1 SF
'''CASE'''
"^*/+-" token →STR POS '''THEN'''
1 CF
'''WHILE''' token <span style="color:blue">POPOP?</span> '''REPEAT'''
'postfix' SWAP STO+
'←depth' DECR DROP
'''END'''
token '←depth' INCR DROP '''END'''
"(" token == '''THEN'''
token '←depth' INCR DROP '''END'''
")" token == '''THEN'''
'''WHILE''' ←depth 1 FS? AND '''REPEAT'''
'''IF''' DUP "(" ≠ '''THEN'''
'postfix' SWAP STO+
'''ELSE''' DROP 1 CF '''END'''
'←depth' DECR DROP
'''END'''
'''END'''
1 FS? '''THEN''' 'postfix' token STO+ '''END'''
'''END'''
'''NEXT'''
'''WHILE''' ←depth '''REPEAT'''
'postfix' SWAP STO+
'←depth' DECR DROP '''END'''
""
1 postfix SIZE '''FOR''' j
postfix j GET + " " + '''NEXT'''
≫ ≫ ‘<span style="color:blue">→RPN<span>’ STO
"3 + 4 * 2 / ( 1 - 5 ) ^ 2 ^ 3" <span style="color:blue">→RPN<span>
{{out}}
<pre>
1: "3 4 2 * 1 5 - 2 3 ^ ^ / + "
</pre>
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