1 files changed, 301 insertions, 0 deletions
diff --git a/tools/glsl_preproc/statement.py b/tools/glsl_preproc/statement.py
new file mode 100644
index 0000000..8641e94
--- /dev/null
+++ b/tools/glsl_preproc/statement.py
@@ -0,0 +1,301 @@
+import re
+
+from templates import GLSL_BLOCK_TEMPLATE
+from variables import VarSet, slugify
+
+VAR_PATTERN = re.compile(flags=re.VERBOSE, pattern=r'''
+    # long form ${ ... } syntax
+    \${ (?:\s*(?P<type>(?:              # optional type prefix
+            ident                       # identifiers (always dynamic)
+          | (?:(?:const|dynamic)\s+)?   # optional const/dynamic modifiers
+                (?:float|u?int)         # base type
+          | swizzle                     # swizzle mask
+          | (?:i|u)?vecType             # vector type (for mask)
+        )):)?
+        (?P<expr>[^{}]+)
+      }
+|   \$(?P<name>\w+) # reference to captured variable
+|   @(?P<var>\w+)   # reference to locally defined var
+''')
+
+class FmtSpec(object):
+    def __init__(self, ctype='ident_t', fmtstr='_%hx',
+                 wrap_expr=lambda name, expr: expr,
+                 fmt_expr=lambda name: name):
+        self.ctype     = ctype
+        self.fmtstr    = fmtstr
+        self.wrap_expr = wrap_expr
+        self.fmt_expr  = fmt_expr
+
+    @staticmethod
+    def wrap_var(type, dynamic=False):
+        if dynamic:
+            return lambda name, expr: f'sh_var_{type}(sh, "{name}", {expr}, true)'
+        else:
+            return lambda name, expr: f'sh_const_{type}(sh, "{name}", {expr})'
+
+    @staticmethod
+    def wrap_fn(fn):
+        return lambda name: f'{fn}({name})'
+
+VAR_TYPES = {
+    # identifiers: get mapped as-is
+    'ident':            FmtSpec(),
+
+    # normal variables: get mapped as shader constants
+    'int':              FmtSpec(wrap_expr=FmtSpec.wrap_var('int')),
+    'uint':             FmtSpec(wrap_expr=FmtSpec.wrap_var('uint')),
+    'float':            FmtSpec(wrap_expr=FmtSpec.wrap_var('float')),
+
+    # constant variables: get printed directly into the source code
+    'const int':        FmtSpec(ctype='int',          fmtstr='%d'),
+    'const uint':       FmtSpec(ctype='unsigned',     fmtstr='uint(%u)'),
+    'const float':      FmtSpec(ctype='float',        fmtstr='float(%f)'),
+
+    # dynamic variables: get loaded as shader variables
+    'dynamic int':      FmtSpec(wrap_expr=FmtSpec.wrap_var('int', dynamic=True)),
+    'dynamic uint':     FmtSpec(wrap_expr=FmtSpec.wrap_var('uint', dynamic=True)),
+    'dynamic float':    FmtSpec(wrap_expr=FmtSpec.wrap_var('float', dynamic=True)),
+
+    # component mask types
+    'swizzle':          FmtSpec(ctype='uint8_t', fmtstr='%s', fmt_expr=FmtSpec.wrap_fn('sh_swizzle')),
+    'ivecType':         FmtSpec(ctype='uint8_t', fmtstr='%s', fmt_expr=FmtSpec.wrap_fn('sh_float_type')),
+    'uvecType':         FmtSpec(ctype='uint8_t', fmtstr='%s', fmt_expr=FmtSpec.wrap_fn('sh_float_type')),
+    'vecType':          FmtSpec(ctype='uint8_t', fmtstr='%s', fmt_expr=FmtSpec.wrap_fn('sh_float_type')),
+}
+
+def stringify(value, strip):
+    end = '\\n"'
+    if strip:
+        end = '"'
+        value = re.sub(r'(?:\/\*[^\*]*\*\/|\/\/[^\n]+|^\s*)', '', value)
+    return '"' + value.replace('\\', '\\\\').replace('"', '\\"') + end
+
+def commentify(value, strip):
+    if strip:
+        return ''
+    return '/*' + value.replace('/*', '[[').replace('*/', ']]') + '*/'
+
+# Represents a statement + its enclosed variables
+class Statement(object):
+    def __init__(self, linenr=0):
+        super().__init__()
+        self.linenr = linenr
+        self.vars = VarSet()
+
+    def add_var(self, ctype, expr, name=None):
+        return self.vars.add_var(ctype, expr, name, self.linenr)
+
+    def render(self):
+        raise NotImplementedError
+
+    @staticmethod
+    def parse(text_orig, **kwargs):
+        raise NotImplementedError
+
+# Represents a single line of GLSL
+class GLSLLine(Statement):
+    class GLSLVar(object): # variable reference
+        def __init__(self, fmt, var):
+            self.fmt = fmt
+            self.var = var
+
+    def __init__(self, text, strip=False, **kwargs):
+        super().__init__(**kwargs)
+        self.refs = []
+        self.strip = strip
+
+        # produce two versions of line, one for printf() and one for append()
+        text = text.rstrip()
+        self.rawstr = stringify(text, strip)
+        self.fmtstr = stringify(re.sub(VAR_PATTERN, self.handle_var, text.replace('%', '%%')), strip)
+
+    def handle_var(self, match):
+        # local @var
+        if match['var']:
+            self.refs.append(match['var'])
+            return '%d'
+
+        # captured $var
+        type = match['type']
+        name = match['name']
+        expr = match['expr'] or name
+        name = name or slugify(expr)
+
+        fmt = VAR_TYPES[type or 'ident']
+        self.refs.append(fmt.fmt_expr(self.add_var(
+            ctype = fmt.ctype,
+            expr  = fmt.wrap_expr(name, expr),
+            name  = name,
+        )))
+
+        if fmt.ctype == 'ident_t':
+            return commentify(name, self.strip) + fmt.fmtstr
+        else:
+            return fmt.fmtstr
+
+# Represents an entire GLSL block
+class GLSLBlock(Statement):
+    def __init__(self, line):
+        super().__init__(linenr=line.linenr)
+        self.lines = []
+        self.refs  = []
+        self.append(line)
+
+    def append(self, line):
+        assert isinstance(line, GLSLLine)
+        self.lines.append(line)
+        self.refs += line.refs
+        self.vars.merge(line.vars)
+
+    def render(self):
+        return GLSL_BLOCK_TEMPLATE.render(block=self)
+
+# Represents a statement which can either take a single line or a block
+class BlockStart(Statement):
+    def __init__(self, multiline=False, **kwargs):
+        super().__init__(**kwargs)
+        self.multiline = multiline
+
+    def add_brace(self, text):
+        if self.multiline:
+            text += ' {'
+        return text
+
+# Represents an @if
+class IfCond(BlockStart):
+    def __init__(self, cond, inner=False, **kwargs):
+        super().__init__(**kwargs)
+        self.cond = cond if inner else self.add_var('bool', expr=cond)
+
+    def render(self):
+        return self.add_brace(f'if ({self.cond})')
+
+# Represents an @else
+class Else(BlockStart):
+    def __init__(self, closing, **kwargs):
+        super().__init__(**kwargs)
+        self.closing = closing
+
+    def render(self):
+        text = '} else' if self.closing else 'else'
+        return self.add_brace(text)
+
+# Represents a normal (integer) @for loop, or an (unsigned 8-bit) bitmask loop
+class ForLoop(BlockStart):
+    def __init__(self, var, op, bound, **kwargs):
+        super().__init__(**kwargs)
+        self.comps = op == ':'
+        self.bound = self.add_var('uint8_t' if self.comps else 'int', expr=bound)
+        self.var   = var
+        self.op    = op
+
+    def render(self):
+        if self.comps:
+            loopstart = f'uint8_t _mask = {self.bound}, {self.var}'
+            loopcond  = f'_mask && ({self.var} = __builtin_ctz(_mask), 1)'
+            loopstep  = f'_mask &= ~(1u << {self.var})'
+        else:
+            loopstart = f'int {self.var} = 0'
+            loopcond  = f'{self.var} {self.op} {self.bound}'
+            loopstep  = f'{self.var}++'
+
+        return self.add_brace(f'for ({loopstart}; {loopcond}; {loopstep})')
+
+# Represents a @switch block
+class Switch(Statement):
+    def __init__(self, expr, **kwargs):
+        super().__init__(**kwargs)
+        self.expr = self.add_var('unsigned', expr=expr)
+
+    def render(self):
+        return f'switch ({self.expr}) {{'
+
+# Represents a @case label
+class Case(Statement):
+    def __init__(self, label, **kwargs):
+        super().__init__(**kwargs)
+        self.label = label
+
+    def render(self):
+        return f'case {self.label}:'
+
+# Represents a @default line
+class Default(Statement):
+    def render(self):
+        return 'default:'
+
+# Represents a @break line
+class Break(Statement):
+    def render(self):
+        return 'break;'
+
+# Represents a single closing brace
+class EndBrace(Statement):
+    def render(self):
+        return '}'
+
+# Shitty regex-based statement parser
+PATTERN_IF  = re.compile(flags=re.VERBOSE, pattern=r'''
+@\s*if\s*                       # '@if'
+(?P<inner>@)?                   # optional leading @
+\((?P<cond>.+)\)\s*             # (condition)
+(?P<multiline>{)?\s*            # optional trailing {
+$''')
+
+PATTERN_ELSE = re.compile(flags=re.VERBOSE, pattern=r'''
+@\s*(?P<closing>})?\s*          # optional leading }
+else\s*                         # 'else'
+(?P<multiline>{)?\s*            # optional trailing {
+$''')
+
+PATTERN_FOR = re.compile(flags=re.VERBOSE, pattern=r'''
+@\s*for\s+\(                    # '@for' (
+(?P<var>\w+)\s*                 # loop variable name
+(?P<op>(?:\<=?|:))(?=[\w\s])\s* # '<', '<=' or ':', followed by \s or \w
+(?P<bound>[^\s].*)\s*           # loop boundary expression
+\)\s*(?P<multiline>{)?\s*       # ) and optional trailing {
+$''')
+
+PATTERN_SWITCH = re.compile(flags=re.VERBOSE, pattern=r'''
+@\s*switch\s*                   # '@switch'
+\((?P<expr>.+)\)\s*{            # switch expression
+$''')
+
+PATTERN_CASE = re.compile(flags=re.VERBOSE, pattern=r'''
+@\s*case\s*                     # '@case'
+(?P<label>[^:]+):?              # case label, optionally followed by :
+$''')
+
+PATTERN_BREAK   = r'@\s*break;?\s*$'
+PATTERN_DEFAULT = r'@\s*default:?\s*$'
+PATTERN_BRACE   = r'@\s*}\s*$'
+
+PARSERS = {
+    PATTERN_IF:         lambda r, **kw: IfCond(r['cond'], inner=r['inner'], multiline=r['multiline'], **kw),
+    PATTERN_ELSE:       lambda r, **kw: Else(closing=r['closing'], multiline=r['multiline'], **kw),
+    PATTERN_FOR:        lambda r, **kw: ForLoop(r['var'], r['op'], r['bound'], multiline=r['multiline'], **kw),
+    PATTERN_SWITCH:     lambda r, **kw: Switch(r['expr'], **kw),
+    PATTERN_CASE:       lambda r, **kw: Case(r['label'], **kw),
+    PATTERN_BREAK:      lambda _, **kw: Break(**kw),
+    PATTERN_DEFAULT:    lambda _, **kw: Default(**kw),
+    PATTERN_BRACE:      lambda _, **kw: EndBrace(**kw),
+}
+
+def parse_line(text_orig, strip, **kwargs):
+    # skip empty lines
+    text = text_orig.strip()
+    if not text:
+        return None
+    if text.lstrip().startswith('@'):
+        # try parsing as statement
+        for pat, fun in PARSERS.items():
+            if res := re.match(pat, text):
+                return fun(res, **kwargs)
+        # return generic error for unrecognized statements
+        raise SyntaxError('Syntax error in directive: ' + text.lstrip())
+    else:
+        # default to literal GLSL line
+        return GLSLLine(text_orig, strip, **kwargs)
+
+Statement.parse = parse_line