Prohibit specifying associativity and precedence multiple times for a symbol

3 files changed, 130 insertions, 1 deletions

diff --git a/grammar/grammar.go b/grammar/grammar.go
index babfb10..c5b8a0c 100644
--- a/grammar/grammar.go
+++ b/grammar/grammar.go
@@ -980,7 +980,7 @@ func (b *GrammarBuilder) genPrecAndAssoc(symTab *symbolTable, prods *productionS
 				})
 				return nil, nil
 			}
-
+		ASSOC_PARAM_LOOP:
 			for _, p := range md.Parameters {
 				if p.ID == "" {
 					b.errs = append(b.errs, &verr.SpecError{
@@ -1011,6 +1011,31 @@ func (b *GrammarBuilder) genPrecAndAssoc(symTab *symbolTable, prods *productionS
 					})
 					return nil, nil
 				}
+				if prec, alreadySet := termPrec[sym.num()]; alreadySet {
+					if prec == precN {
+						b.errs = append(b.errs, &verr.SpecError{
+							Cause:  semErrDuplicateAssoc,
+							Detail: fmt.Sprintf("'%v' already has the same associativity and precedence", p.ID),
+							Row:    p.Pos.Row,
+							Col:    p.Pos.Col,
+						})
+					} else if assoc := termAssoc[sym.num()]; assoc == assocTy {
+						b.errs = append(b.errs, &verr.SpecError{
+							Cause:  semErrDuplicateAssoc,
+							Detail: fmt.Sprintf("'%v' already has different precedence", p.ID),
+							Row:    p.Pos.Row,
+							Col:    p.Pos.Col,
+						})
+					} else {
+						b.errs = append(b.errs, &verr.SpecError{
+							Cause:  semErrDuplicateAssoc,
+							Detail: fmt.Sprintf("'%v' already has different associativity and precedence", p.ID),
+							Row:    p.Pos.Row,
+							Col:    p.Pos.Col,
+						})
+					}
+					break ASSOC_PARAM_LOOP
+				}
 
 				termPrec[sym.num()] = precN
 				termAssoc[sym.num()] = assocTy
@@ -1019,6 +1044,9 @@ func (b *GrammarBuilder) genPrecAndAssoc(symTab *symbolTable, prods *productionS
 			precN++
 		}
 	}
+	if len(b.errs) > 0 {
+		return nil, nil
+	}
 
 	prodPrec := map[productionNum]int{}
 	prodAssoc := map[productionNum]assocType{}
diff --git a/grammar/grammar_test.go b/grammar/grammar_test.go
index 40c07aa..a90ee8b 100644
--- a/grammar/grammar_test.go
+++ b/grammar/grammar_test.go
@@ -442,6 +442,56 @@ foo
 `,
 			errs: []*SemanticError{semErrMDInvalidParam},
 		},
+		{
+			caption: "the `%left` cannot be specified multiple times for a symbol",
+			specSrc: `
+%name test
+
+%left foo foo
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []*SemanticError{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a symbol cannot have different precedence",
+			specSrc: `
+%name test
+
+%left foo
+%left foo
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []*SemanticError{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a symbol cannot have different associativity",
+			specSrc: `
+%name test
+
+%right foo
+%left foo
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []*SemanticError{semErrDuplicateAssoc},
+		},
 	}
 
 	rightTests := []*specErrTest{
@@ -525,6 +575,56 @@ foo
 `,
 			errs: []*SemanticError{semErrMDInvalidParam},
 		},
+		{
+			caption: "the `%right` cannot be specified multiple times for a symbol",
+			specSrc: `
+%name test
+
+%right foo foo
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []*SemanticError{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a symbol cannot have different precedence",
+			specSrc: `
+%name test
+
+%right foo
+%right foo
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []*SemanticError{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a symbol cannot have different associativity",
+			specSrc: `
+%name test
+
+%left foo
+%right foo
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []*SemanticError{semErrDuplicateAssoc},
+		},
 	}
 
 	errorSymTests := []*specErrTest{
diff --git a/grammar/semantic_error.go b/grammar/semantic_error.go
index 8e5b558..c013cbc 100644
--- a/grammar/semantic_error.go
+++ b/grammar/semantic_error.go
@@ -18,6 +18,7 @@ var (
 	semErrMDInvalidName       = newSemanticError("invalid meta data name")
 	semErrMDInvalidParam      = newSemanticError("invalid parameter")
 	semErrMDMissingName       = newSemanticError("name is missing")
+	semErrDuplicateAssoc      = newSemanticError("associativity and precedence cannot be specified multiple times for a symbol")
 	semErrUnusedProduction    = newSemanticError("unused production")
 	semErrUnusedTerminal      = newSemanticError("unused terminal")
 	semErrTermCannotBeSkipped = newSemanticError("a terminal used in productions cannot be skipped")