parser: add ToolContext#parse_something

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/parser_util.nit b/src/parser_util.nit
index ed43555..91e766d 100644 (file)
--- a/src/parser_util.nit
+++ b/src/parser_util.nit
@@ -15,7 +15,7 @@
 # Utils and tools related to parsers and AST
 module parser_util
 
-import parser
+intrude import parser
 import toolcontext
 
 redef class ToolContext
@@ -82,6 +82,111 @@ redef class ToolContext
                var nexpr = nmodule.n_classdefs.first.n_propdefs.first.as(AMainMethPropdef).n_block.as(ABlockExpr).n_expr.first.as(AVardeclExpr).n_expr.as(not null)
                return nexpr
        end
+
+       # Try to parse the `string` as something
+       #
+       # Returns the first possible syntacticaly correct type among:
+       #
+       # - a type `AType`
+       # - a single `Token`
+       # - an expression `AExpr`
+       # - a block of statements `ABlockExpr`
+       # - a full module `AModule`
+       # - a `AError` if nothing else matches
+       fun parse_something(string: String): ANode
+       do
+               var source = new SourceFile.from_string("", string)
+               var error
+               var tree
+               var eof
+               var lexer
+
+               lexer = new InjectedLexer(source)
+               lexer.injected_before.add new TKwvar
+               lexer.injected_before.add new TId
+               lexer.injected_before.add new TColumn
+               lexer.injected_before.add new TClassid
+               lexer.injected_before.add new TObra
+               lexer.injected_after.add new TCbra
+               tree = (new Parser(lexer)).parse
+               eof = tree.n_eof
+               if not eof isa AError then
+                       var ntype = tree.n_base.n_classdefs.first.n_propdefs.first.as(AMainMethPropdef).n_block.as(ABlockExpr).n_expr.first.as(AVardeclExpr).n_type.n_types.first
+                       return ntype
+               end
+               error = eof
+
+               lexer = new Lexer(source)
+               var first = lexer.next
+               if not first isa EOF then
+                       var second = lexer.next
+                       if second isa EOF and not second isa AError then
+                               return first
+                       end
+               end
+
+               lexer = new InjectedLexer(source)
+               lexer.injected_before.add new TKwvar
+               lexer.injected_before.add new TId
+               lexer.injected_before.add new TAssign
+               lexer.injected_before.add new TOpar
+               lexer.injected_after.add new TCpar
+               tree = (new Parser(lexer)).parse
+               eof = tree.n_eof
+               if not eof isa AError then
+                       var nexpr = tree.n_base.n_classdefs.first.n_propdefs.first.as(AMainMethPropdef).n_block.as(ABlockExpr).n_expr.first.as(AVardeclExpr).n_expr.as(AParExpr).n_expr
+                       return nexpr
+               end
+               if eof.location > error.location then error = eof
+
+               lexer = new InjectedLexer(source)
+               lexer.injected_before.add new TKwdo
+               lexer.injected_after.add new TKwend
+               tree = (new Parser(lexer)).parse
+               eof = tree.n_eof
+               if not eof isa AError then
+                       var nblock = tree.n_base.n_classdefs.first.n_propdefs.first.as(AMainMethPropdef).n_block.as(ABlockExpr).n_expr.first.as(ADoExpr).n_block.as(not null)
+                       return nblock
+               end
+               if eof.location > error.location then error = eof
+
+               lexer = new Lexer(source)
+               tree = (new Parser(lexer)).parse
+               eof = tree.n_eof
+               if not eof isa AError then
+                       return tree.n_base.as(not null)
+               end
+               if eof.location > error.location then error = eof
+
+               return error
+       end
+end
+
+class InjectedLexer
+       super Lexer
+
+       var injected_before = new List[Token]
+       var injected_after = new List[Token]
+       private var is_finished = false
+
+       redef fun get_token
+       do
+               if not injected_before.is_empty then
+                       var tok = injected_before.shift
+                       if tok._location == null then tok._location = new Location(file, 1, 1, 1, 0)
+                       return tok
+               end
+               if not is_finished then
+                       var next = super
+                       if not next isa EOF then return next
+                       injected_after.push(next)
+                       is_finished = true
+               end
+
+               var tok = injected_after.shift
+               if tok._location == null then tok._location = new Location(file, 1, 1, 1, 0)
+               return tok
+       end
 end
 
 redef class ANode