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Unexpect abmbigious grammar [message #1740830]

Thu, 18 August 2016 18:45

kozhaev Vladimir

Messages: 108
Registered: July 2009

Senior Member

Hi all, I have create xtext grammar and have warnings(see it bellow) I understand that XText have generated ambigious ANTLR grammar, but don't understand why.
So, what is wrong in my grammar?

Regards,
Vladimir

grammar com.idc.net.Validator with org.eclipse.xtext.common.Terminals

generate validator "http://www.idc.com/net/Validator"

Model:
	netDescriptions+=NetDescription+;

NetDescription:
	descriptionPairs+=DescriptionPair+;

DescriptionPair:
	IPADDR | NETMASK | SPEED | MTU | TSO | GATEWAY | VLAN | ROUTER | SUBNET | NO_VLANS | VLAN;
//List of numbers with 3 digit
 VLAN:
	'VLAN_' name=ID '='
	value=IntList;

IntList:
	valueList+=INT+ | '"' valueList+=INT+ '"';

IPAddrList:
	ipNum1=INT '.' ipNum2=INT '.' ipNum3=INT '.' ipNum4=INT;

//List of numbers with 3 digit
 NO_VLANS:
	'NO_VLANS_' name=ID '=' list+=IntList;

SUBNET:
	'SUBNET_' name=ID '=' list+=IPWithQuotes;

ROUTER:
	'ROUTER_' name=ID '=' list+=IPWithQuotes;

GATEWAY:
	'GATEWAY_' name=ID '=' list+=IPWithQuotes;

MTU:
	'MTU_' name=ID '=' val=IntWithQuotes;

TSO:
	'TSO_' name=ID '=' '"' value=ON_OFF '"';

ON_OFF:
	'on' | 'off';

NETMASK:
	'NETMASK_' name=ID '=' list+=IPWithQuotes;

SPEED:
	'SPEED_' name=ID '=' value=IntWithQuotes;

IPADDR:
	'IPADDR_' name=ID '=' list+=IPWithQuotes;

IPWithQuotes:
	IPAddrList | '"' IPAddrList '"';

IntWithQuotes:
	value=INT | '"' value=INT '"';

warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'SPEED_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'GATEWAY_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'VLAN_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'IPADDR_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'MTU_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'TSO_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'NO_VLANS_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'NETMASK_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'ROUTER_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:132:2: Decision can match input such as "'SUBNET_'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:150:2: Decision can match input such as "'VLAN_' RULE_ID '=' RULE_INT" using multiple alternatives: 7, 11
As a result, alternative(s) 11 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:150:2: Decision can match input such as "'VLAN_' RULE_ID '=' '"' RULE_INT '"'" using multiple alternatives: 7, 11
As a result, alternative(s) 11 were disabled for that input
error(201): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:150:2: The following alternatives can never be matched: 11

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Re: Unexpect abmbigious grammar [message #1740831 is a reply to message #1740830]

Thu, 18 August 2016 18:50

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

If you have a model with

Speed_ s1 = "1"
Speed_ s2 = "2"

Should that give one model with two net descriptions with one pair each
Or should that give one model with one description with two pairs?

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: Unexpect abmbigious grammar [message #1740843 is a reply to message #1740831]

Thu, 18 August 2016 21:23

kozhaev Vladimir

Messages: 108
Registered: July 2009

Senior Member

Oh, look like I'm wrong in my grammar. Actually I don't need NetDescription rule, jast pairs.
So, now my grammar is following with other(but look like with the same sence) How to fix it?

Regards,
Vladimir

grammar com.idc.net.Validator with org.eclipse.xtext.common.Terminals

generate validator "http://www.idc.com/net/Validator"

Model:
	netDescription+=DescriptionPair+;

DescriptionPair:
	IPADDR | NETMASK | SPEED | MTU | TSO | GATEWAY | VLAN | ROUTER | SUBNET | NO_VLANS | VLAN;
//List of numbers with 3 digit
 VLAN:
	'VLAN_' name=ID '='
	value=IntList;

IntList:
	valueList+=INT+ | '"' valueList+=INT+ '"';

IPAddrList:
	ipNum1=INT '.' ipNum2=INT '.' ipNum3=INT '.' ipNum4=INT;

//List of numbers with 3 digit
 NO_VLANS:
	'NO_VLANS_' name=ID '=' list+=IntList;

SUBNET:
	'SUBNET_' name=ID '=' list+=IPWithQuotes;

ROUTER:
	'ROUTER_' name=ID '=' list+=IPWithQuotes;

GATEWAY:
	'GATEWAY_' name=ID '=' list+=IPWithQuotes;

MTU:
	'MTU_' name=ID '=' val=IntWithQuotes;

TSO:
	'TSO_' name=ID '=' '"' value=ON_OFF '"';

ON_OFF:
	'on' | 'off';

NETMASK:
	'NETMASK_' name=ID '=' list+=IPWithQuotes;

SPEED:
	'SPEED_' name=ID '=' value=IntWithQuotes;

IPADDR:
	'IPADDR_' name=ID '=' list+=IPWithQuotes;

IPWithQuotes:
	IPAddrList | '"' IPAddrList '"';

IntWithQuotes:
	value=INT | '"' value=INT '"';

warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:114:2: Decision can match input such as "'VLAN_' RULE_ID '=' RULE_INT" using multiple alternatives: 7, 11
As a result, alternative(s) 11 were disabled for that input
warning(200): ../com.idc.net.validator/src-gen/com/idc/net/parser/antlr/internal/InternalValidator.g:114:2: Decision can match input such as "'VLAN_' RULE_ID '=' '"' RULE_INT '"'" using multiple alternatives: 7, 11
As a result, alternative(s) 11 were disabled for that input

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