Renamed cspan_at2 .. at4 to cspan_subdim2 .. Improved cspan docs.

3 files changed, 58 insertions, 53 deletions

diff --git a/docs/cspan_api.md b/docs/cspan_api.md
index 8cabd97e..d6caff4e 100644
--- a/docs/cspan_api.md
+++ b/docs/cspan_api.md
@@ -10,78 +10,83 @@ See the c++ classes [std::span](https://en.cppreference.com/w/cpp/container/span
 
 ```c
 #include <stc/cspan.h>
-using_cspan(SpanType, ValueType, Rank);     // define SpanType with ValueType elements.
-                                            // Rank is number of dimensions (max 4)
+using_cspan(SpanType, ValueType, Rank); // define SpanType with ValueType elements.
+                                        // Rank is number of dimensions (max 4)
 // Shorthands:
-using_cspan2(S, ValueType);                 // define span types S, S2 with ranks 1, 2.
-using_cspan3(S, ValueType);                 // define span types S, S2, S3 with ranks 1, 2, 3.
-using_cspan4(S, ValueType);                 // define span types S, S2, S3, S4 with ranks 1, 2, 3, 4.
+using_cspan2(S, ValueType);             // define span types S, S2 with ranks 1, 2.
+using_cspan3(S, ValueType);             // define span types S, S2, S3 with ranks 1, 2, 3.
+using_cspan4(S, ValueType);             // define span types S, S2, S3, S4 with ranks 1, 2, 3, 4.
 ```
 ## Methods
 Note that `cspan_make()`, `cmake_from*()`, `cspan_atN()`, `and cspan_subspanN()` require a (safe) cast to its span-type
 on assignment, but not on initialization of a span variable. All functions are type-safe, and arguments are side-effect safe, except for SpanType arg. which must not have side-effects.
 ```c
-SpanType{N}     cspan_make(ValueType* data,  size_t xdim, ...);         // make N-dimensional cspan
+SpanTypeN       cspan_make(ValueType* data,  size_t xdim, ...);         // make N-dimensional cspan
 SpanType        cspan_from(STCContainer* cnt);                          // create a 1D cspan from a compatible STC container
 SpanType        cspan_from_array(ValueType array[]);                    // create a 1D cspan from a C array
 
-void            cspan_resize(SpanType{N}* self, size_t xdim, ...);      // change the extent of each dimension
+void            cspan_resize(SpanTypeN* self, size_t xdim, ...);        // change the extent of each dimension
 
-size_t          cspan_size(const SpanType{N}* self);                    // return number of elements
-unsigned        cspan_rank(const SpanType{N}* self);                    // return number of dimensions
-size_t          cspan_index(const SpanType{N}* self, size_t x, ...);    // index of element
+size_t          cspan_size(const SpanTypeN* self);                      // return number of elements
+unsigned        cspan_rank(const SpanTypeN* self);                      // return number of dimensions
+size_t          cspan_index(const SpanTypeN* self, size_t x, ...);      // index of element
                 
-ValueType*      cspan_at(SpanType{N}* self, size_t x, ...);             // at(): num of args decides input SpanType{N}.
-SpanType        cspan_at2(SpanType2* self, size_t x);                   // return a 1D subarray cspan.
-SpanType{N}     cspan_at3(SpanType3* self, size_t x, ...);              // atN(): N decides input SpanType,
-SpanType{N}     cspan_at4(SpanType4* self, size_t x, ...);              // and num of args decides returned SpanType{N}.
-
-SpanType        cspan_subspan(const SpanType* self, size_t offset, size_t count);  // return a slice of a 1D cspan
-SpanType2       cspan_subspan2(const SpanType2 self, size_t offset, size_t count); // return a slice of a 2D cspan
-SpanType3       cspan_subspan3(const SpanType3 self, size_t offset, size_t count); // return a slice of a 3D cspan
-SpanType4       cspan_subspan4(const SpanType4 self, size_t offset, size_t count); // return a slice of a 4D cspan
-
-SpanType{N}_iter    SpanType_begin(const SpanType{N}* self);
-SpanType{N}_iter    SpanType_end(const SpanType{N}* self);
-void                SpanType_next(SpanType{N}_iter* it);
+ValueType*      cspan_at(SpanTypeN* self, size_t x, ...);               // at(): num of args decides input SpanTypeN.
+ValueType*      cspan_front(SpanTypeN* self);
+ValueType*      cspan_back(SpanTypeN* self);
+
+SpanType        cspan_subdim2(SpanType2* self, size_t x);               // return a cspan from a 2D SpanType.
+SpanTypeN       cspan_subdim3(SpanType3* self, size_t x, ...);          // subdimN(): N decides input SpanType,
+SpanTypeN       cspan_subdim4(SpanType4* self, size_t x, ...);          // and num of args decides returned SpanTypeN.
+
+                // return a subspan of same rank:
+SpanType        cspan_subspan(const SpanType* self, size_t offset, size_t count);
+SpanType2       cspan_subspan2(const SpanType2 self, size_t offset, size_t count);
+SpanType3       cspan_subspan3(const SpanType3 self, size_t offset, size_t count);
+SpanType4       cspan_subspan4(const SpanType4 self, size_t offset, size_t count);
+
+SpanTypeN_iter  SpanType_begin(const SpanTypeN* self);
+SpanTypeN_iter  SpanType_end(const SpanTypeN* self);
+void            SpanType_next(SpanTypeN_iter* it);
 ```
 ## Types
 
-| Type name           | Type definition                                | Used to represent... |
-|:--------------------|:-----------------------------------------------|:---------------------|
-| SpanType{N}         | `struct { ValueType *data; uint32_t dim[N]; }` | SpanType with rank N |
-| SpanType{N}`_value` | `ValueType`                                    | The ValueType        |
-| SpanType{N}`_iter`  | `struct { ValueType *ref; ... }`               | Iterator type        |
+| Type name         | Type definition                                | Used to represent... |
+|:------------------|:-----------------------------------------------|:---------------------|
+| SpanTypeN         | `struct { ValueType *data; uint32_t dim[N]; }` | SpanType with rank N |
+| SpanTypeN`_value` | `ValueType`                                    | The ValueType        |
+| SpanTypeN`_iter`  | `struct { ValueType *ref; ... }`               | Iterator type        |
 
 ## Example
 ```c
 #include <stdio.h>
+#include <stc/cspan.h>
 #define i_val float
 #include <stc/cstack.h>
 
-#include <stc/cspan.h>
-using_cspan3(FS, float); // Shorthand to define span types FS, FS2, and FS3.
+using_cspan3(Span, float); // Shorthand to define span types Span, Span2, and Span3.
 
 int main()
 {
     int xd = 6, yd = 4, zd = 3;
-    c_AUTO (cstack_float, vec) {
+    c_AUTO (cstack_float, vec)
+    {
         c_FORRANGE (i, xd*yd*zd)
             cstack_float_push(&vec, i);
 
         // define "span3[xd][yd][zd]"
-        FS3 span3 = cspan_make(vec.data, xd, yd, zd);
-        *cspan_at(&span3, 4, 3, 2) = 3.14f;
+        Span3 span3 = cspan_make(vec.data, xd, yd, zd);
+        *cspan_at(&span3, 4, 3, 2) = 3.14159f;
         printf("index: %d", (int)cspan_index(&span3, 4, 3, 2));
 
-        FS span1 = cspan_at3(&span3, 4, 3);
+        Span span1 = cspan_subdim3(&span3, 4, 3);
         printf("\niterate span1: ");
-        c_FOREACH (i, FS, span1)
+        c_FOREACH (i, Span, span1)
             printf("%g ", *i.ref);
 
-        FS2 span2 = cspan_at3(&span3, 4);
+        Span2 span2 = cspan_subdim3(&span3, 4);
         printf("\niterate span2: ");
-        c_FOREACH (i, FS2, span2)
+        c_FOREACH (i, Span2, span2)
             printf("%g ", *i.ref);
 
         puts("\niterate span3 by dimensions:");
@@ -103,16 +108,16 @@ int main()
 Output:
 ```
 index: 59
-iterate span1: 57 58 3.14
-iterate span2: 48 49 50 51 52 53 54 55 56 57 58 3.14
+iterate span1: 57 58 3.14159 
+iterate span2: 48 49 50 51 52 53 54 55 56 57 58 3.14159 
 iterate span3 by dimensions:
- 0 1 2 | 3 4 5 | 6 7 8 | 9 10 11 |
+  0  1  2 |  3  4  5 |  6  7  8 |  9 10 11 |
  12 13 14 | 15 16 17 | 18 19 20 | 21 22 23 |
  24 25 26 | 27 28 29 | 30 31 32 | 33 34 35 |
  36 37 38 | 39 40 41 | 42 43 44 | 45 46 47 |
- 48 49 50 | 51 52 53 | 54 55 56 | 57 58 3.14 |
+ 48 49 50 | 51 52 53 | 54 55 56 | 57 58 3.14159 |
  60 61 62 | 63 64 65 | 66 67 68 | 69 70 71 |
-3.14
-3.14
-3.14
+3.14159
+3.14159
+3.14159
 ```
diff --git a/include/stc/cspan.h b/include/stc/cspan.h
index 88e10b07..96439c64 100644
--- a/include/stc/cspan.h
+++ b/include/stc/cspan.h
@@ -120,19 +120,19 @@ int demo2() {
 #define cspan_subspan4(self, offset, count) \
     {.data=cspan_at(self, offset, 0, 0, 0), .dim={count, (self)->dim[1], (self)->dim[2], (self)->dim[3]}}
 
-#define cspan_at4(...) c_MACRO_OVERLOAD(cspan_at4, __VA_ARGS__)
-#define cspan_at3(...) c_MACRO_OVERLOAD(cspan_at3, __VA_ARGS__)
-#define cspan_at2(self, x) \
+#define cspan_subdim4(...) c_MACRO_OVERLOAD(cspan_subdim4, __VA_ARGS__)
+#define cspan_subdim3(...) c_MACRO_OVERLOAD(cspan_subdim3, __VA_ARGS__)
+#define cspan_subdim2(self, x) \
     {.data=cspan_at(self, x, 0), .dim={(self)->dim[1]}}
-#define cspan_at32(self, x) \
+#define cspan_subdim32(self, x) \
     {.data=cspan_at(self, x, 0, 0), .dim={(self)->dim[1], (self)->dim[2]}}
-#define cspan_at33(self, x, y) \
+#define cspan_subdim33(self, x, y) \
     {.data=cspan_at(self, x, y, 0), .dim={(self)->dim[2]}}
-#define cspan_at42(self, x) \
+#define cspan_subdim42(self, x) \
     {.data=cspan_at(self, x, 0, 0, 0), .dim={(self)->dim[1], (self)->dim[2], (self)->dim[3]}}
-#define cspan_at43(self, x, y) \
+#define cspan_subdim43(self, x, y) \
     {.data=cspan_at(self, x, y, 0, 0), .dim={(self)->dim[2], (self)->dim[3]}}
-#define cspan_at44(self, x, y, z) \
+#define cspan_subdim44(self, x, y, z) \
     {.data=cspan_at(self, x, y, z, 0), .dim={(self)->dim[3]}}
 
 STC_INLINE size_t _cspan_i1(const uint32_t dim[1], uint32_t x)
diff --git a/misc/examples/multidim.c b/misc/examples/multidim.c
index 945741b1..e882d62a 100644
--- a/misc/examples/multidim.c
+++ b/misc/examples/multidim.c
@@ -36,7 +36,7 @@ int main()
   puts("");
 
   // or iterate a subspan...
-  ispan2 sub = cspan_at3(&ms3, 1);
+  ispan2 sub = cspan_subdim3(&ms3, 1);
   printf("sub: ");
   c_FOREACH (i, ispan2, sub)
     printf(" %d", *i.ref);