Math generator: add limit (#60)

Bug:#56

CMakeLists.txt

@@ -30,7 +30,6 @@ endif()
 
 FetchContent_Declare(antlr
   GIT_REPOSITORY https://github.com/antlr/antlr4
-  # GIT_TAG 4.11.1
   GIT_TAG 1cb4669f84cea5b59661fd44b0f80509fdacd3f9
   GIT_SHALLOW FALSE
   GIT_PROGRESS TRUE

snap/snapcraft.yaml

@@ -15,7 +15,7 @@ base: core20
 icon: "./favicon.png"
 apps:
   diagon:
-    command: diagon
+    command: usr/local/bin/diagon
 
 parts:
   diagon:
@@ -31,8 +31,8 @@ parts:
       - uuid-dev
       - openjdk-11-jdk
       - libboost-graph-dev
-    override-build: |
-      snapcraftctl build
+    override-pull: |
+      snapcraftctl pull
       snapcraftctl set-version "$(git rev-list --count HEAD)"
     cmake-parameters:
       - -DCMAKE_INSTALL_PREFIX=/usr

src/translator/math/Math.cpp

@@ -30,6 +30,7 @@ struct Style {
   wchar_t multiply;
   std::wstring lower_or_equal;
   std::wstring greater_or_equal;
+  std::wstring lime;
 
   wchar_t left_parenthesis_0;
   wchar_t left_parenthesis_1;
@@ -76,8 +77,8 @@ Draw Parse(MathParser::ValueBangContext* context, Style*, bool);
 Draw Parse(MathParser::ValueContext*, Style*, bool suppress_parenthesis);
 Draw Parse(MathParser::AtomContext*, Style*, bool suppress_parenthesis);
 Draw Parse(MathParser::VariableContext*, Style* style);
-Draw ComposeHorizontal(const Draw& left, const Draw& right, int spaces);
-Draw ComposeVertical(const Draw& top, const Draw& down, int spaces);
+Draw ComposeHorizontal(const Draw& left, const Draw& right, int spaces = 0);
+Draw ComposeVertical(const Draw& top, const Draw& down, int spaces = 0);
 Draw ComposeDiagonal(const Draw& A, const Draw& B);
 Draw WrapWithParenthesis(const Draw& element, Style* style);
 std::string to_string(const Draw& draw);
@@ -293,6 +294,7 @@ Draw Parse(MathParser::EquationContext* context, Style* style) {
     else if (op->LE()) symbol = style->lower_or_equal;
     else if (op->GE()) symbol = style->greater_or_equal;
     else if (op->EQ()) symbol = L'=';
+    else if (op->LIME()) symbol = style->lime;
     // clang-format on
 
     int op_x = draw.dim_x + 1;
@@ -317,6 +319,7 @@ std::wstring ParseLatex(MathParser::EquationContext* context, Style* style) {
     else if (op->GT()) out += L" > ";
     else if (op->LE()) out += L" \\leq ";
     else if (op->GE()) out += L" \\geq ";
+    else if (op->LIME()) out += L" \\to ";
     else if (op->EQ()) out += L" = ";
     // clang-format on
 
@@ -540,6 +543,57 @@ std::wstring ParseFunctionSumLatex(MathParser::FunctionContext* context,
   return out + L" " + ParseLatex(context->equation(0), style);
 }
 
+bool CheckFunctionLimit(MathParser::FunctionContext* context) {
+  int num_arguments = context->equation().size();
+  if (num_arguments != 2) {
+    std::cerr << "Limit function (lim) only handle 2 arguments, but "
+              << num_arguments << " provided" << std::endl;
+    return false;
+  }
+  return true;
+}
+
+Draw ParseFunctionLimit(MathParser::FunctionContext* context, Style* style) {
+  if (!CheckFunctionLimit(context))
+    return Draw(L"(error)");
+
+  Draw lim = Parse(context->variable(), style);
+  Draw down = Parse(context->equation(0), style);
+  Draw right = Parse(context->equation(1), style);
+
+  if (right.center_y == right.dim_y-1) {
+    Draw lim_right = ComposeHorizontal(lim, right, 1);
+    lim_right.center_x = 0;
+    down.center_x = 0;
+    Draw out = ComposeVertical(lim_right, down);
+    out.center_x = lim_right.dim_x - 1;
+    out.center_y = 0;
+    return out;
+  }
+
+  // Align center `lim` with `down`.
+  lim.center_x = 0;
+  down.center_x = 0;
+  Draw lim_down = ComposeVertical(std::move(lim), std::move(down));
+
+  // Align |lim_down| and right to the correct baseline.
+  lim_down.center_x = lim.dim_x / 2;
+  lim_down.center_y = 0;
+  right.center_x = right.dim_x / 2;
+  return ComposeHorizontal(std::move(lim_down), std::move(right), 1);
+}
+
+std::wstring ParseFunctionLimitLatex(MathParser::FunctionContext* context,
+                                     Style* style) {
+  if (!CheckFunctionLimit(context))
+    return L"(error)";
+
+  std::wstring out = L"\\lim";
+  if (context->equation(0))
+    out += L"_{" + ParseLatex(context->equation(0), style) + L"}";
+  return out + L" " + ParseLatex(context->equation(1), style);
+}
+
 bool CheckFunctionMult(MathParser::FunctionContext* context) {
   int num_arguments = context->equation().size();
   if (num_arguments > 3) {
@@ -799,6 +853,8 @@ Draw Parse(MathParser::FunctionContext* context, Style* style) {
     return ParseFunctionSqrt(context, style);
   if (function_name == "sum")
     return ParseFunctionSum(context, style);
+  if (function_name == "lim")
+    return ParseFunctionLimit(context, style);
   if (function_name == "int")
     return ParseFunctionIntegral(context, style);
   if (function_name == "mult")
@@ -834,6 +890,8 @@ std::wstring ParseLatex(MathParser::FunctionContext* context, Style* style) {
     return ParseFunctionSqrtLatex(context, style);
   if (function_name == "sum")
     return ParseFunctionSumLatex(context, style);
+  if (function_name == "lim")
+    return ParseFunctionLimitLatex(context, style);
   if (function_name == "int")
     return ParseFunctionIntegralLatex(context, style);
   if (function_name == "mult")
@@ -1064,38 +1122,88 @@ class Math : public Translator {
 
   std::vector<Translator::Example> Examples() final {
     return {
-        {"1-fraction", "f(x) = 1 + x / (1 + x)"},
-        {"2-square-root", "sqrt(1+sqrt(1+x/2))"},
-        {"3-power", "f(x) = 1 + x^2 + x^3 + x^(1+1/2)"},
-        {"4-subscript", "S_n = u_1 + u_2 + ... + u_n"},
-        {"5-summation", "sum(i^2,i=0,n) = n^3/2+n^2/2+n/6"},
-        {"6-integral", "int(x^2 * dx ,0,1) = n^3/3"},
-        {"7-product",
-         "mult(i^2,i=1,n) = (mult(i,i=1,n))^2\n\n\n\nmult(1/2,1,100) = "
-         "7.8886091e-31"},
-        {"8-vector", "[a;b] + [c;d] = [a+c; b+d]"},
-        {"9-matrix", "[1,2;3,4] * [x;y] = [1*x+2*y; 3*x+4*y]"},
-        {"10-factorial", "[n;k] = n! / (k! *(n-k)!)"},
-        {"11-quoted-string",
-         "\"x_n\"\n"
-         " x_n\n"},
-        {"12-braces-vs-parenthesis",
-         "A_(1+2)\n"
-         "\n"
-         "A_{1+2}\n"
-         "\n"
-         "A^{1+2}\n"},
-        {"13-Math-symbols",
-         "Alpha + alpha + Digamma + digamma + Kappa + kappa + Omicron \n"
-         "omicron + Upsilon + upsilon + Beta + beta + Zeta + zeta + Lambda \n"
-         "lambda + Pi + pi + Phi + phi + Gamma + gamma + Eta + eta + Mu + mu \n"
-         "Rho + rho + Chi + chi + Delta + delta + Theta + theta + Nu + nu \n"
-         "Sigma + sigma + Psi + psi + Epsilon + epsilon + Iota + iota + Xi\n"
-         "xi + Tau + tau + Omega + omega"},
-        {"14-mathbb",
-         "mathbb(R)\n\nbb(R)\n\nbb(ABCDEFGHIJKLMNOPQRSTUVWXYZ)\n\nbb("
-         "abcdefghijklmnopqrstuvwxyz)\n\nbb(0123456789)"},
-        {"100-continued-fraction", "psi = 1 + 1/(1+1/(1+1/(1+1/(1+...))))"},
+        {
+            "1-fraction",
+            "f(x) = 1 + x / (1 + x)",
+        },
+        {
+            "2-square-root",
+            "sqrt(1+sqrt(1+x/2))",
+        },
+        {
+            "3-power",
+            "f(x) = 1 + x^2 + x^3 + x^(1+1/2)",
+        },
+        {
+            "4-subscript",
+            "S_n = u_1 + u_2 + ... + u_n",
+        },
+        {
+            "5-summation",
+            "sum(i^2,i=0,n) = n^3/2+n^2/2+n/6",
+        },
+        {
+            "6-integral",
+            "int(x^2 * dx ,0,1) = n^3/3",
+        },
+        {
+            "7-product",
+            "mult(i^2,i=1,n) = (mult(i,i=1,n))^2\n\n\n\nmult(1/2,1,100) = "
+            "7.8886091e-31",
+        },
+        {
+            "8-vector",
+            "[a;b] + [c;d] = [a+c; b+d]",
+        },
+        {
+            "9-matrix",
+            "[1,2;3,4] * [x;y] = [1*x+2*y; 3*x+4*y]",
+        },
+        {
+            "10-factorial",
+            "[n;k] = n! / (k! *(n-k)!)",
+        },
+        {
+            "11-quoted-string",
+            "\"x_n\"\n"
+            " x_n\n",
+        },
+        {
+            "12-braces-vs-parenthesis",
+            "A_(1+2)\n"
+            "\n"
+            "A_{1+2,}\n"
+            "\n"
+            "A^{1+2,}\n",
+        },
+        {
+            "13-Math-symbols",
+            "Alpha + alpha + Digamma + digamma + Kappa + kappa + Omicron \n"
+            "omicron + Upsilon + upsilon + Beta + beta + Zeta + zeta + Lambda "
+            "\n"
+            "lambda + Pi + pi + Phi + phi + Gamma + gamma + Eta + eta + Mu + "
+            "mu \n"
+            "Rho + rho + Chi + chi + Delta + delta + Theta + theta + Nu + nu \n"
+            "Sigma + sigma + Psi + psi + Epsilon + epsilon + Iota + iota + Xi\n"
+            "xi + Tau + tau + Omega + omega",
+        },
+        {
+            "14-mathbb",
+            "mathbb(R)\n\nbb(R)\n\nbb(ABCDEFGHIJKLMNOPQRSTUVWXYZ)\n\nbb("
+            "abcdefghijklmnopqrstuvwxyz)\n\nbb(0123456789)",
+        },
+        {
+            "100-continued-fraction",
+            "psi = 1 + 1/(1+1/(1+1/(1+1/(1+...))))",
+        },
+        {
+            "15-limits",
+            "lim(x -> infinity, 1/x) = 0",
+        },
+        {
+            "100-continued-fraction",
+            "psi = 1 + 1/(1+1/(1+1/(1+1/(1+...))))",
+        },
     };
   }
 
@@ -1107,6 +1215,7 @@ class Math : public Translator {
       style.divide = L'-';
       style.multiply = L'.';
       style.greater_or_equal = L">=";
+      style.lime= L"->";
       style.lower_or_equal = L"<=";
       style.left_parenthesis_0 = L'(';
       style.left_parenthesis_1 = L'/';
@@ -1139,6 +1248,7 @@ class Math : public Translator {
       // style.multiply = L'×';
       style.multiply = L'⋅';
       style.greater_or_equal = L"≥";
+      style.lime= L"⟶";
       style.lower_or_equal = L"≤";
 
       style.left_parenthesis_0 = L'(';

src/translator/math/Math.g4

@@ -59,7 +59,7 @@ function : variable LPAREN equation (',' equation)* RPAREN ;
 variable : VARIABLE;
 matrix : LBRACKET matrixLine (';' matrixLine)* RBRACKET;
 matrixLine : expression ( ',' expression ) *;
-relop : EQ | GT | LT | GE | LE;
+relop : EQ | GT | LT | GE | LE | LIME;
 addop : PLUS | MINUS ;
 mulop : TIMES | DIV ;
 powop : POW | SUBSCRIPT ;
@@ -77,6 +77,7 @@ MINUS : '-' ;
 TIMES : '*' ;
 BANG: '!';
 DIV : '/' ;
+LIME : '->' ; 
 GT : '>' ; 
 LT : '<' ; 
 GE : '>=' ; 

test/Math/lim/input

@@ -0,0 +1,7 @@
+lim(a,b)
+
+lim(x->infinity, x) = infinity
+
+lim(x->∞, sqrt(x+1/x)) = infinity
+
+lim(x->∞, sqrt(x+1/x)) = 1/2

test/Math/lim/output

@@ -0,0 +1,15 @@
+lim b              
+a                  
+
+lim x = ∞          
+x ⟶ ∞              
+
+          _____    
+         ╱    1    
+lim     ╱ x + ─ = ∞
+x ⟶ ∞ ╲╱      x    
+
+          _____    
+         ╱    1   1
+lim     ╱ x + ─ = ─
+x ⟶ ∞ ╲╱      x   2

test/Math_style=ASCII/lim/input

@@ -0,0 +1,7 @@
+lim(a,b)
+
+lim(x->infinity, x) = infinity
+
+lim(x->∞, sqrt(x+1/x)) = infinity
+
+lim(x->∞, sqrt(x+1/x)) = 1/2

test/Math_style=ASCII/lim/output

@@ -0,0 +1,15 @@
+lim b               
+a                   
+
+lim x  = ∞          
+x -> ∞              
+
+           _____    
+          /    1    
+lim      / x + - = ∞
+x -> ∞ \/      x    
+
+           _____    
+          /    1   1
+lim      / x + - = -
+x -> ∞ \/      x   2

test/Math_style=Latex/lim/input

@@ -0,0 +1,7 @@
+lim(a,b)
+
+lim(x->infinity, x) = infinity
+
+lim(x->∞, sqrt(x+1/x)) = infinity
+
+lim(x->∞, sqrt(x+1/x)) = 1/2

test/Math_style=Latex/lim/output

@@ -0,0 +1,7 @@
+\lim_{a} b \\
+\\
+\lim_{x \to \infty} x = \infty \\
+\\
+\lim_{x \to ∞} \sqrt{x + \frac{1}{x}} = \infty \\
+\\
+\lim_{x \to ∞} \sqrt{x + \frac{1}{x}} = \frac{1}{2}