This paper describes linguistic tools specifically designed for performant automatic indexing of natural language texts. By performant indexing, we mean the ability of the system to extract noun phrases (considered as main conceptual frames regarding text content) without processing full syntactic analysis of sentences (surface analyzer) both with its ability in learning unknown words. The paper describes the overall principles of this parser, emphasizing the use of syntactic networks and precedence matrix to fulfil the above goals of reducing the analysis cost and infering new vocabularies without interrupting the indexing process.