WGRAMMAR: Leverage Prior Knowledge to Accelerate Structured Decoding

Fuente: arXiv
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Autores principales: Wang, Ran, Liu, Xiaoxuan, Ren, Hao, Chen, Gang, Qi, Fanchao, Sun, Maosong
Formato: Preprint
Publicado: 2025
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author Wang, Ran
Liu, Xiaoxuan
Ren, Hao
Chen, Gang
Qi, Fanchao
Sun, Maosong
author_facet Wang, Ran
Liu, Xiaoxuan
Ren, Hao
Chen, Gang
Qi, Fanchao
Sun, Maosong
contents Structured decoding enables large language models (LLMs) to generate outputs in formats required by downstream systems, such as HTML or JSON. However, existing methods suffer from efficiency bottlenecks due to grammar compilation, state tracking, and mask creation. We observe that many real-world tasks embed strong prior knowledge about output structure. Leveraging this, we propose a decomposition of constraints into static and dynamic components -- precompiling static structures offline and instantiating dynamic arguments at runtime using grammar snippets. Instead of relying on pushdown automata, we employ a compositional set of operators to model regular formats, achieving lower transition latency. We introduce wgrammar, a lightweight decoding engine that integrates domain-aware simplification, constraint decomposition, and mask caching, achieving up to 250x speedup over existing systems. wgrammar's source code is publicly available at https://github.com/wrran/wgrammar.
format Preprint
id arxiv_https___arxiv_org_abs_2507_16768
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle WGRAMMAR: Leverage Prior Knowledge to Accelerate Structured Decoding
Wang, Ran
Liu, Xiaoxuan
Ren, Hao
Chen, Gang
Qi, Fanchao
Sun, Maosong
Artificial Intelligence
Structured decoding enables large language models (LLMs) to generate outputs in formats required by downstream systems, such as HTML or JSON. However, existing methods suffer from efficiency bottlenecks due to grammar compilation, state tracking, and mask creation. We observe that many real-world tasks embed strong prior knowledge about output structure. Leveraging this, we propose a decomposition of constraints into static and dynamic components -- precompiling static structures offline and instantiating dynamic arguments at runtime using grammar snippets. Instead of relying on pushdown automata, we employ a compositional set of operators to model regular formats, achieving lower transition latency. We introduce wgrammar, a lightweight decoding engine that integrates domain-aware simplification, constraint decomposition, and mask caching, achieving up to 250x speedup over existing systems. wgrammar's source code is publicly available at https://github.com/wrran/wgrammar.
title WGRAMMAR: Leverage Prior Knowledge to Accelerate Structured Decoding
topic Artificial Intelligence
url https://arxiv.org/abs/2507.16768