InvokeAI/ldm/dream/conditioning.py

'''
This module handles the generation of the conditioning tensors, including management of
weighted subprompts.

Useful function exports:

get_uc_and_c()                  get the conditioned and unconditioned latent
split_weighted_subpromopts()    split subprompts, normalize and weight them
log_tokenization()              print out colour-coded tokens and warn if truncated

'''
import re
import torch

def get_uc_and_c(prompt, model, log_tokens=False, skip_normalize=False):
    uc = model.get_learned_conditioning([''])

    # get weighted sub-prompts
    weighted_subprompts = split_weighted_subprompts(
        prompt, skip_normalize
    )

    if len(weighted_subprompts) > 1:
        # i dont know if this is correct.. but it works
        c = torch.zeros_like(uc)
        # normalize each "sub prompt" and add it
        for subprompt, weight in weighted_subprompts:
            log_tokenization(subprompt, model, log_tokens)
            c = torch.add(
                c,
                model.get_learned_conditioning([subprompt]),
                alpha=weight,
            )
    else:   # just standard 1 prompt
        log_tokenization(prompt, model, log_tokens)
        c = model.get_learned_conditioning([prompt])
    return (uc, c)

def split_weighted_subprompts(text, skip_normalize=False)->list:
    """
    grabs all text up to the first occurrence of ':'
    uses the grabbed text as a sub-prompt, and takes the value following ':' as weight
    if ':' has no value defined, defaults to 1.0
    repeats until no text remaining
    """
    prompt_parser = re.compile("""
            (?P<prompt>     # capture group for 'prompt'
            (?:\\\:|[^:])+  # match one or more non ':' characters or escaped colons '\:'
            )               # end 'prompt'
            (?:             # non-capture group
            :+              # match one or more ':' characters
            (?P<weight>     # capture group for 'weight'
            -?\d+(?:\.\d+)? # match positive or negative integer or decimal number
            )?              # end weight capture group, make optional
            \s*             # strip spaces after weight
            |               # OR
            $               # else, if no ':' then match end of line
            )               # end non-capture group
            """, re.VERBOSE)
    parsed_prompts = [(match.group("prompt").replace("\\:", ":"), float(
        match.group("weight") or 1)) for match in re.finditer(prompt_parser, text)]
    if skip_normalize:
        return parsed_prompts
    weight_sum = sum(map(lambda x: x[1], parsed_prompts))
    if weight_sum == 0:
        print(
            "Warning: Subprompt weights add up to zero. Discarding and using even weights instead.")
        equal_weight = 1 / len(parsed_prompts)
        return [(x[0], equal_weight) for x in parsed_prompts]
    return [(x[0], x[1] / weight_sum) for x in parsed_prompts]
        
# shows how the prompt is tokenized
# usually tokens have '</w>' to indicate end-of-word,
# but for readability it has been replaced with ' '
def log_tokenization(text, model, log=False):
    if not log:
        return
    tokens    = model.cond_stage_model.tokenizer._tokenize(text)
    tokenized = ""
    discarded = ""
    usedTokens = 0
    totalTokens = len(tokens)
    for i in range(0, totalTokens):
        token = tokens[i].replace('</w>', ' ')
        # alternate color
        s = (usedTokens % 6) + 1
        if i < model.cond_stage_model.max_length:
            tokenized = tokenized + f"\x1b[0;3{s};40m{token}"
            usedTokens += 1
        else:  # over max token length
            discarded = discarded + f"\x1b[0;3{s};40m{token}"
        print(f"\n>> Tokens ({usedTokens}):\n{tokenized}\x1b[0m")
        if discarded != "":
            print(
                f">> Tokens Discarded ({totalTokens-usedTokens}):\n{discarded}\x1b[0m"
            )