feat(api): add range syntax to expand numbered tokens (#179)

api/onnx_web/diffusers/utils.py

@@ -1,5 +1,6 @@
 from logging import getLogger
 from math import ceil
+from re import compile
 from typing import List, Optional
 
 import numpy as np
@@ -7,7 +8,18 @@ from diffusers import OnnxStableDiffusionPipeline
 
 logger = getLogger(__name__)
 
+
 MAX_TOKENS_PER_GROUP = 77
+PATTERN_RANGE = compile("(\w+)-{(\d+),(\d+)(?:,(\d+))?}")
+
+
+def expand_prompt_ranges(prompt: str) -> str:
+    def expand_range(match):
+        (base_token, start, end, step) = match.groups(default=1)
+        num_tokens = [f"{base_token}-{i}" for i in range(int(start), int(end), int(step))]
+        return " ".join(num_tokens)
+
+    return PATTERN_RANGE.sub(expand_range, prompt)
 
 
 def expand_prompt(
@@ -22,6 +34,7 @@ def expand_prompt(
     #   encoder: OnnxRuntimeModel
 
     batch_size = len(prompt) if isinstance(prompt, list) else 1
+    prompt = expand_prompt_ranges(prompt)
 
     # split prompt into 75 token chunks
     tokens = self.tokenizer(