Simplify the syntax of #ast directive

This change allows using the simple syntax of the directive like `#ast $1 $3...` instead of `#ast #(foo $1 $3...)`.

1 files changed, 8 insertions, 10 deletions

diff --git a/spec/syntax_error.go b/spec/syntax_error.go
index a35a90c..ae65b35 100644
--- a/spec/syntax_error.go
+++ b/spec/syntax_error.go
@@ -25,14 +25,12 @@ var (
 	synErrZeroPos           = newSyntaxError("a position must be greater than or equal to 1")
 
 	// syntax errors
-	synErrInvalidToken         = newSyntaxError("invalid token")
-	synErrNoProductionName     = newSyntaxError("a production name is missing")
-	synErrNoColon              = newSyntaxError("the colon must precede alternatives")
-	synErrNoSemicolon          = newSyntaxError("the semicolon is missing at the last of an alternative")
-	synErrNoDirectiveName      = newSyntaxError("a directive needs a name")
-	synErrProdDirNoNewline     = newSyntaxError("a production directive must be followed by a newline")
-	synErrSemicolonNoNewline   = newSyntaxError("a semicolon must be followed by a newline")
-	synErrFragmentNoPattern    = newSyntaxError("a fragment needs one pattern element")
-	synErrTreeInvalidFirstElem = newSyntaxError("the first element of a tree structure must be an ID")
-	synErrTreeUnclosed         = newSyntaxError("unclosed tree structure")
+	synErrInvalidToken       = newSyntaxError("invalid token")
+	synErrNoProductionName   = newSyntaxError("a production name is missing")
+	synErrNoColon            = newSyntaxError("the colon must precede alternatives")
+	synErrNoSemicolon        = newSyntaxError("the semicolon is missing at the last of an alternative")
+	synErrNoDirectiveName    = newSyntaxError("a directive needs a name")
+	synErrProdDirNoNewline   = newSyntaxError("a production directive must be followed by a newline")
+	synErrSemicolonNoNewline = newSyntaxError("a semicolon must be followed by a newline")
+	synErrFragmentNoPattern  = newSyntaxError("a fragment needs one pattern element")
 )