Parsing a function call (e.g. `exp '(' exp ')'`) in Bison: results in shift/reduce errors (precedence issue)

By -

I'm trying to parse a function call (currently just one argument, but I'll allow for several when I get it working).

Suppose exp is defined as

%left '+'
%precedence CALL

exp:
    exp '+' exp { ... }
|   exp '(' exp ')' %prec CALL { ... }
|   LITERAL { ... }
;

This creates an ambiguity. If I use -Wcounterexamples then it says that exp '+' exp · '(' exp ')' could be parsed in 2 ways, either shifting or reducing at the '('.

calc.y: warning: shift/reduce conflict on token '(' [-Wcounterexamples]
  Example: exp '+' exp • '(' exp ')'
  Shift derivation
    exp
    ↳ exp '+' exp
              ↳ exp • '(' exp ')'
  Example: exp '+' exp • '(' exp ')'
  Reduce derivation
    exp
    ↳ exp             '(' exp ')'
      ↳ exp '+' exp •

It appears that it doesn't know that a call should have a precedence that is higher or lower than +. What can I do to make sure that it knows that x+y(z) should be equivalent to x+(y(z)) and not (x+y)(z)?

Bison: strange shift-reduce conflict seems related.



from Recent Questions - Stack Overflow https://ift.tt/2PanSEk
https://ift.tt/eA8V8J

Comments

Post a Comment

Popular posts from this blog

Today Walkin 14th-Sept

By -
Image
14th Sept 2017 ( GO Through all List) Read Walkin details properly , Try to call company before attending if possible !!! ==================================== 1. Myntra through fresherworld (Call Based , Venue shared to shortlisted candidates) _____________________________ 2. Magna : Hiring for Client Harman : C++
Read more

Hibernate Search - Elasticsearch with JSON manipulation

By -
Elasticsearch with JSON manipulation Elasticsearch ships with many features. It is possible that at some point, one feature you need will not be exposed by the Search DSL. To work around such limitations, Hibernate Search provides ways to: Transform the HTTP request sent to Elasticsearch for search queries. Read the raw JSON of the HTTP response received from Elasticsearch for search queries. Direct changes to the HTTP request may conflict with Hibernate Search features and be supported differently by different versions of Elasticsearch. Similarly, the content of the HTTP response may change depending on the version of Elasticsearch, depending on which Hibernate Search features are used, and even depending on how Hibernate Search features are implemented. Thus, features relying on direct access to HTTP requests or responses cannot be guaranteed to continue to work when upgrading Hibernate Search, even for micro upgrades (x.y.z to x.y.(z+1)). Use this at your own risk.
Read more

Spring Elasticsearch Operations

By -
Elasticsearch Operations Spring Data Elasticsearch uses two interfaces to define the operations that can be called against an Elasticsearch index. These are ElasticsearchOperations and ReactiveElasticsearchOperations. Whereas the first is used with the classic synchronous implementations, the second one uses reactive infrastructure. The default implementations of the interfaces offer: Read/Write mapping support for domain types. A rich query and criteria api. Resource management and Exception translation. ElasticsearchTemplate The ElasticsearchTemplate is an implementation of the ElasticsearchOperations interface using the Transport Client. @Configuration public class TransportClientConfig extends ElasticsearchConfigurationSupport {   @Bean   public Client elasticsearchClient() throws UnknownHostException {                      Settings settings = Settings.builder().put("cluster.name", "elasticsearch").build();     TransportClient client = new P
Read more