[Grammar] Add support for env();

Add support for `env(ENV,default)`.

Fixes: #1411

doc/rofi-theme.5.markdown

@@ -470,6 +470,23 @@ window {
 }
 ```
 
+* Format: `var(PROPERTY NAME, DEFAULT)`
+
+A reference can point to another reference. Currently, the maximum number of redirects is 20.
+A property always refers to another property. It cannot be used for a subpart of the property.
+
+Example:
+
+```css
+window {
+    width: var( width, 30%);
+}
+```
+
+If the property `width` is set globally (`*{}`) that value is used, if the property
+`width` is not set, the default value is used.
+
+
 ## Orientation
 
  * Format: `(horizontal|vertical)`
@@ -502,6 +519,20 @@ The environment variable should be an alphanumeric string without white-space.
 }
 ```
 
+* Format: `env(ENVIRONMENT, default)`
+
+This will parse the environment variable as the property value. (that then can be any of the above types).
+The environment variable should be an alphanumeric string without white-space.
+If the environment value is not found, the default value is used.
+
+```css
+window {
+    width: env(WIDTH, 40%);
+}
+```
+
+If environment WIDTH is set, then that value is parsed, otherwise the default value (`40%`).
+
 ## Inherit
 
  * Format: `inherit`

lexer/theme-lexer.l

@@ -273,6 +273,7 @@ LIST_OPEN        \[
 LIST_CLOSE       \]
 
 VAR_START  "var"
+ENV_START  "env"
 
 CPP_COMMENT  "//"
 C_COMMENT_OPEN "/*"
@@ -290,6 +291,7 @@ CONFIGURATION (?i:configuration)
 %x PROPERTIES
 %x PROPERTIES_ENV
 %x PROPERTIES_VAR
+%x PROPERTIES_ENV_VAR
 %x PROPERTIES_VAR_DEFAULT
 %x PROPERTIES_LIST
 %x NAMESTR
@@ -491,7 +493,7 @@ if ( queue == NULL ) {
 
   /* After Namestr/Classstr we want to go to state str, then to  { */
 <INITIAL,SECTION>{WHITESPACE}+	; // ignore all whitespace
-<PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT,PROPERTIES_LIST,PROPERTIES_VAR,MEDIA_CONTENT>{WHITESPACE}+	; // ignore all whitespace
+<PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT,PROPERTIES_LIST,PROPERTIES_ENV_VAR,PROPERTIES_VAR,MEDIA_CONTENT>{WHITESPACE}+	; // ignore all whitespace
 
 <SECTION>":"                      { g_queue_push_head ( queue, GINT_TO_POINTER (YY_START) ); BEGIN(PROPERTIES); return T_PSEP; }
 <PROPERTIES>";"                   { BEGIN(GPOINTER_TO_INT ( g_queue_pop_head ( queue ))); return T_PCLOSE;}
@@ -550,6 +552,26 @@ if ( queue == NULL ) {
         g_queue_push_head ( queue, GINT_TO_POINTER (YY_START) ); BEGIN(PROPERTIES_ENV);
     }
 }
+<PROPERTIES_ENV_VAR>{WORD} {
+    const char *val = g_getenv(yytext);
+    if ( val ) {
+        ParseObject *top = g_queue_peek_head ( file_queue );
+        top->location = *yylloc;
+        ParseObject *po = g_malloc0(sizeof(ParseObject));
+        po->type = PT_ENV;
+        po->input_str = val;
+        po->str_len = strlen(val);
+        current = po;
+        g_queue_push_head ( file_queue, po );
+
+        yypush_buffer_state (yy_create_buffer ( 0, YY_BUF_SIZE ));
+        yylloc->first_line = yylloc->last_line = 1;
+        yylloc->first_column = yylloc->last_column = 1;
+        yylloc->filename = current->filename;
+        g_queue_push_head ( queue, GINT_TO_POINTER (YY_START) ); BEGIN(PROPERTIES_ENV);
+    }
+}
+
 
  /**
   * Color parsing. It is easier to do this at lexer level.
@@ -610,17 +632,26 @@ if ( queue == NULL ) {
 <PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT>{HSL}              { return T_COL_HSL;        }
 <PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT>{HWB}              { return T_COL_HWB;        }
 <PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT>{CMYK}             { return T_COL_CMYK;       }
- /* Fluff */
-<PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT>{VAR_START}{S_T_PARENT_LEFT}        {
-    g_queue_push_head ( queue, GINT_TO_POINTER (YY_START) );
-    BEGIN(PROPERTIES_VAR);
+
+<PROPERTIES_ENV_VAR,PROPERTIES_VAR>{S_T_PARENT_LEFT} {
     return T_PARENT_LEFT;
 }
-<PROPERTIES_VAR>{S_T_PARENT_RIGHT} {
+ /* Fluff */
+<PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT>{VAR_START} {
+    g_queue_push_head ( queue, GINT_TO_POINTER (YY_START) );
+    BEGIN(PROPERTIES_VAR);
+    return T_VAR_START;
+}
+<PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT>{ENV_START} {
+    g_queue_push_head ( queue, GINT_TO_POINTER (YY_START) );
+    BEGIN(PROPERTIES_ENV_VAR);
+    return T_ENV_START;
+}
+<PROPERTIES_VAR,PROPERTIES_ENV_VAR>{S_T_PARENT_RIGHT} {
     BEGIN(GPOINTER_TO_INT(g_queue_pop_head ( queue )));
     return T_PARENT_RIGHT;
 }
-<PROPERTIES_VAR>{COMMA} {
+<PROPERTIES_VAR,PROPERTIES_ENV_VAR>{COMMA} {
     g_queue_push_head ( queue, GINT_TO_POINTER (YY_START) );
     BEGIN(PROPERTIES_VAR_DEFAULT);
     return T_COMMA;
@@ -794,7 +825,7 @@ if ( queue == NULL ) {
     return T_ELEMENT;
 }
 
-<PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT,PROPERTIES_LIST>. {
+<PROPERTIES_ENV_VAR,PROPERTIES_VAR,PROPERTIES,PROPERTIES_ENV,PROPERTIES_VAR_DEFAULT,PROPERTIES_LIST>. {
     yytext[yyleng-1] = '\0';
     return T_ERROR_PROPERTY;
 }

lexer/theme-parser.y

@@ -265,6 +265,10 @@ static ThemeColor hwb_to_rgb ( double h, double w, double b )
 %token T_MEDIA_MAX                      "Max"
 %token T_MEDIA_SEP                      "-"
 
+
+%token T_VAR_START                      "var" 
+%token T_ENV_START                      "env" 
+
 %type <theme>          t_entry_list
 %type <theme>          t_entry_list_included
 %type <list>           t_entry_name_path
@@ -481,17 +485,25 @@ t_property
     $$ = $3;
     $$->name = $1;
    }
-|   t_property_name T_PSEP T_PARENT_LEFT T_ELEMENT T_PARENT_RIGHT T_PCLOSE{
+|   t_property_name T_PSEP T_VAR_START T_PARENT_LEFT T_ELEMENT T_PARENT_RIGHT T_PCLOSE{
         $$ = rofi_theme_property_create ( P_LINK );
         $$->name = $1;
-        $$->value.link.name = $4;
+        $$->value.link.name = $5;
     }
-|   t_property_name T_PSEP T_PARENT_LEFT T_ELEMENT T_COMMA t_property_element T_PARENT_RIGHT T_PCLOSE{
+|   t_property_name T_PSEP T_VAR_START T_PARENT_LEFT T_ELEMENT T_COMMA t_property_element T_PARENT_RIGHT T_PCLOSE{
         $$ = rofi_theme_property_create ( P_LINK );
         $$->name = $1;
-        $$->value.link.name = $4;
-        $$->value.link.def_value = $6;
+        $$->value.link.name = $5;
+        $$->value.link.def_value = $7;
     }
+| t_property_name T_PSEP T_ENV_START T_PARENT_LEFT T_COMMA t_property_element T_PARENT_RIGHT T_PCLOSE {
+  $$ = $6;
+  $$->name = $1;
+}
+| t_property_name T_PSEP T_ENV_START T_PARENT_LEFT t_property_element T_COMMA t_property_element T_PARENT_RIGHT T_PCLOSE {
+  $$ = $5;
+  $$->name = $1;
+}
 
 t_property_element
 :   T_INHERIT {

meson.build

@@ -134,7 +134,7 @@ flex = generator(find_program('flex'),
 )
 bison = generator(find_program('bison'),
     output: [ '@BASENAME@.c', '@BASENAME@.h' ],
-    arguments: [ '-d', '@INPUT@', '--defines=@OUTPUT1@', '--output=@OUTPUT0@' ]
+    arguments: [ '--verbose', '-d', '@INPUT@', '--defines=@OUTPUT1@', '--output=@OUTPUT0@' ]
 )
 
 rofi_sources = files(