Supprt simple inline set statements

OHM is a PEG-based grammar parser generator which seems to be more
compatible with the Jinja language. We are not making use of their
automatic space handling since in Jinja whitespace is significant.

grammar/jinja.ohm

@@ -0,0 +1,180 @@
+Jinja {
+  Template
+    = expressions
+    
+    expressions
+    = expression*
+    
+    expression
+    = content
+    | inlineStatement
+    | blockStatement
+
+	blockStatement
+    = blockStatement_open expressions blockStatement_close
+    
+    blockStatement_open
+    = statementOpen sp? blockStatementOpenContent sp? statementClose
+    
+    blockStatementOpenContent
+    = statement_block
+    | statement_filter
+    | statement_setBlock
+    
+    blockStatement_close
+    = statementOpen sp? blockStatementCloseContent sp? statementClose
+
+	blockStatementCloseContent
+    = statementEnd_block
+    | blockStatementCloseContent_generic
+
+	blockStatementCloseContent_generic
+    = blockStatementId_end blockStatementId_list
+
+    inlineStatement
+    = statementOpen sp? inlineStatementContent sp? statementClose
+    
+    inlineStatementContent
+    = statement_extends
+    | statement_from
+    | statement_import
+    | statement_include
+    | statement_setInline
+    
+    statement_block
+    = statementId_block sp identifier (sp contextModifier_scoped)? (sp contextModifier_required)?
+    
+    statementEnd_block
+    = blockStatementId_end statementId_block (sp identifier)?
+    
+    statement_extends
+    = statementId_extends sp statementExtends_file
+    
+    statementExtends_file
+    = stringLiteral
+    | variableName
+    
+    statement_filter
+    = statementId_filter sp filterExpression
+    
+    statement_from
+    = statementId_from sp statementImport_file sp statementId_import sp statementFrom_variables (sp importOptions_contextManagement)?
+    
+    statementFrom_variables
+    = (statementFrom_variable sp? comma sp?)* statementFrom_variable
+    statementFrom_variable = variableName (sp statementModifier_as sp variableName)?
+    
+    statement_import
+    = statementId_import sp statementImport_file sp statementModifier_as sp variableName
+    
+    statementImport_file
+    = stringLiteral
+    | variableName
+    
+    statement_include
+    = statementId_include sp statementInclude_file (sp importOptions_ignoreMissing)? (sp importOptions_contextManagement)?
+    
+    statementInclude_file
+    = stringLiteral
+    | listLiteral
+    | variableName
+    
+    statement_setInline
+    = statementId_set sp variableName sp? equals sp? statementSet_value
+    
+    statementSet_value
+    = stringLiteral
+    | variableName
+    | listLiteral
+    | explicitTupleLiteral
+    
+    statement_setBlock
+    = statementId_set sp variableName (sp verticalBar sp filterExpression)*
+    
+    content
+    = (~statementOpen any)+
+    
+    variableName = identifier
+    
+    filterExpression
+    = filter_center
+    | filter_upper
+    | filter_wordWrap
+    
+    filter_center = filterId_center (parenthesis_left sp? filterCenter_parameters? sp? parenthesis_right)?
+    
+    filterCenter_parameters = digit+
+    
+    filter_upper = filterId_upper
+    filter_wordWrap = filterId_wordWrap
+    
+    filterId_center = "center"
+    filterId_upper = "upper"
+    filterId_wordWrap = "wordwrap"
+    
+    statementOpen = "{%"
+    statementClose = "%}"
+    
+	statementId_block = "block"
+	statementId_extends = "extends"
+    statementId_filter = "filter"
+    statementId_from = "from"
+    statementId_import = "import"
+    statementId_include = "include"
+    statementId_set = "set"
+    
+    blockStatementId_list
+    = statementId_block
+    | statementId_filter
+    | statementId_set
+    
+    blockStatementId_end = "end"
+    
+    statementModifier_as = "as"
+    
+    contextModifier_scoped = "scoped"
+    contextModifier_required = "required"
+    
+    importOptions_ignoreMissing = "ignore missing"
+    importOptions_contextManagement = importOptions_withContext | importOptions_withoutContext
+    importOptions_withContext = "with context"
+    importOptions_withoutContext = "without context"
+    
+    listLiteral = bracket_left listLiteral_values? bracket_right
+    listLiteral_values = sp? (listLiteral_value sp? comma sp?)* listLiteral_value sp?
+    listLiteral_value
+    = stringLiteral
+    | explicitTupleLiteral
+    | variableName
+    
+    stringLiteral = stringLiteral_single | stringLiteral_double
+    
+    stringLiteral_single = quote_single (~quote_single any)* quote_single
+    stringLiteral_double = quote_double (~quote_double any)* quote_double
+    
+    explicitTupleLiteral = parenthesis_left sp? tupleLiteral_values sp? parenthesis_right
+    
+    tupleLiteral_values = (sp? tupleLiteral_value sp? comma sp?)* tupleLiteral_value
+    tupleLiteral_value
+    = stringLiteral
+
+	quote_single = "'"
+    quote_double = "\""
+    comma = ","
+    equals = "="
+    verticalBar = "|"
+    
+    bracket_left = "["
+    bracket_right = "]"
+    brace_left = "{"
+    brace_right = "}"
+    parenthesis_left = "("
+    parenthesis_right = ")"
+    
+    identifier = identifierStart identifierContinue*
+    
+    identifierStart = letter
+    identifierContinue = letter | digit | "_"
+
+    sp = (" " | "\t")+
+}