Add precedences and associativities to the description file

4 files changed, 85 insertions, 14 deletions

diff --git a/cmd/vartan/describe.go b/cmd/vartan/describe.go
index d9c3b01..c2cde93 100644
--- a/cmd/vartan/describe.go
+++ b/cmd/vartan/describe.go
@@ -153,12 +153,40 @@ func writeDescription(w io.Writer, desc *spec.Description) error {
 			return "No conflict was detected."
 		},
 		"printTerminal": func(term spec.Terminal) string {
+			var prec string
+			if term.Precedence != 0 {
+				prec = fmt.Sprintf("%2v", term.Precedence)
+			} else {
+				prec = " -"
+			}
+
+			var assoc string
+			if term.Associativity != "" {
+				assoc = term.Associativity
+			} else {
+				assoc = "-"
+			}
+
 			if term.Alias != "" {
-				return fmt.Sprintf("%4v %v (%v)", term.Number, term.Name, term.Alias)
+				return fmt.Sprintf("%4v %v %v %v (%v)", term.Number, prec, assoc, term.Name, term.Alias)
 			}
-			return fmt.Sprintf("%4v %v", term.Number, term.Name)
+			return fmt.Sprintf("%4v %v %v %v", term.Number, prec, assoc, term.Name)
 		},
 		"printProduction": func(prod spec.Production) string {
+			var prec string
+			if prod.Precedence != 0 {
+				prec = fmt.Sprintf("%2v", prod.Precedence)
+			} else {
+				prec = " -"
+			}
+
+			var assoc string
+			if prod.Associativity != "" {
+				assoc = prod.Associativity
+			} else {
+				assoc = "-"
+			}
+
 			var b strings.Builder
 			fmt.Fprintf(&b, "%v →", nonTermName(prod.LHS))
 			if len(prod.RHS) > 0 {
@@ -173,7 +201,7 @@ func writeDescription(w io.Writer, desc *spec.Description) error {
 				fmt.Fprintf(&b, " ε")
 			}
 
-			return fmt.Sprintf("%4v %v", prod.Number, b.String())
+			return fmt.Sprintf("%4v %v %v %v", prod.Number, prec, assoc, b.String())
 		},
 		"printItem": func(item spec.Item) string {
 			prod := desc.Productions[item.Production]
diff --git a/grammar/grammar.go b/grammar/grammar.go
index edfb6af..b87d368 100644
--- a/grammar/grammar.go
+++ b/grammar/grammar.go
@@ -33,8 +33,9 @@ const (
 // precAndAssoc represents precedence and associativities of terminal symbols and productions.
 // We use the priority of the production to resolve shift/reduce conflicts.
 type precAndAssoc struct {
-	// termPrec represents the precedence of the terminal symbols.
-	termPrec map[symbolNum]int
+	// termPrec and termAssoc represent the precedence of the terminal symbols.
+	termPrec  map[symbolNum]int
+	termAssoc map[symbolNum]assocType
 
 	// prodPrec and prodAssoc represent the precedence and the associativities of the production.
 	// These values are inherited from the right-most symbols in the RHS of the productions.
@@ -51,6 +52,15 @@ func (pa *precAndAssoc) terminalPrecedence(sym symbolNum) int {
 	return prec
 }
 
+func (pa *precAndAssoc) terminalAssociativity(sym symbolNum) assocType {
+	assoc, ok := pa.termAssoc[sym]
+	if !ok {
+		return assocTypeNil
+	}
+
+	return assoc
+}
+
 func (pa *precAndAssoc) productionPredence(prod productionNum) int {
 	prec, ok := pa.prodPrec[prod]
 	if !ok {
@@ -896,6 +906,7 @@ func (b *GrammarBuilder) genPrecAndAssoc(symTab *symbolTable, prods *productionS
 
 	return &precAndAssoc{
 		termPrec:  termPrec,
+		termAssoc: termAssoc,
 		prodPrec:  prodPrec,
 		prodAssoc: prodAssoc,
 	}, nil
diff --git a/grammar/parsing_table.go b/grammar/parsing_table.go
index fe5a619..a82ef60 100644
--- a/grammar/parsing_table.go
+++ b/grammar/parsing_table.go
@@ -347,6 +347,19 @@ func (b *lrTableBuilder) genDescription(tab *ParsingTable, gram *Grammar) (*spec
 				term.Pattern = pat
 			}
 
+			prec := b.precAndAssoc.terminalPrecedence(sym.num())
+			if prec != precNil {
+				term.Precedence = prec
+			}
+
+			assoc := b.precAndAssoc.terminalAssociativity(sym.num())
+			switch assoc {
+			case assocTypeLeft:
+				term.Associativity = "l"
+			case assocTypeRight:
+				term.Associativity = "r"
+			}
+
 			terms[sym.num()] = term
 		}
 	}
@@ -382,11 +395,26 @@ func (b *lrTableBuilder) genDescription(tab *ParsingTable, gram *Grammar) (*spec
 				}
 			}
 
-			prods[p.num.Int()] = &spec.Production{
+			prod := &spec.Production{
 				Number: p.num.Int(),
 				LHS:    p.lhs.num().Int(),
 				RHS:    rhs,
 			}
+
+			prec := b.precAndAssoc.productionPredence(p.num)
+			if prec != precNil {
+				prod.Precedence = prec
+			}
+
+			assoc := b.precAndAssoc.productionAssociativity(p.num)
+			switch assoc {
+			case assocTypeLeft:
+				prod.Associativity = "l"
+			case assocTypeRight:
+				prod.Associativity = "r"
+			}
+
+			prods[p.num.Int()] = prod
 		}
 	}
 
diff --git a/spec/description.go b/spec/description.go
index d2b6d3b..08b037e 100644
--- a/spec/description.go
+++ b/spec/description.go
@@ -1,11 +1,13 @@
 package spec
 
 type Terminal struct {
-	Number    int    `json:"number"`
-	Name      string `json:"name"`
-	Anonymous bool   `json:"anonymous"`
-	Alias     string `json:"alias"`
-	Pattern   string `json:"pattern"`
+	Number        int    `json:"number"`
+	Name          string `json:"name"`
+	Anonymous     bool   `json:"anonymous"`
+	Alias         string `json:"alias"`
+	Pattern       string `json:"pattern"`
+	Precedence    int    `json:"prec"`
+	Associativity string `json:"assoc"`
 }
 
 type NonTerminal struct {
@@ -14,9 +16,11 @@ type NonTerminal struct {
 }
 
 type Production struct {
-	Number int   `json:"number"`
-	LHS    int   `json:"lhs"`
-	RHS    []int `json:"rhs"`
+	Number        int    `json:"number"`
+	LHS           int    `json:"lhs"`
+	RHS           []int  `json:"rhs"`
+	Precedence    int    `json:"prec"`
+	Associativity string `json:"assoc"`
 }
 
 type Item struct {